GPLize project

Finally deciding to move things into a proper license; which I can do
since I've never accepted (or had :( ) a pull request from another
person

117 files changed, 2290 insertions, 109 deletions

diff --git a/src/main/java/bjc/data/ArrayIterator.java b/src/main/java/bjc/data/ArrayIterator.java
index c5f68cc..f89210f 100644
--- a/src/main/java/bjc/data/ArrayIterator.java
+++ b/src/main/java/bjc/data/ArrayIterator.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.Iterator;
diff --git a/src/main/java/bjc/data/BooleanToggle.java b/src/main/java/bjc/data/BooleanToggle.java
index e0286d4..56cbdf0 100644
--- a/src/main/java/bjc/data/BooleanToggle.java
+++ b/src/main/java/bjc/data/BooleanToggle.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 /**
diff --git a/src/main/java/bjc/data/CircularIterator.java b/src/main/java/bjc/data/CircularIterator.java
index ce6b4c3..a718524 100644
--- a/src/main/java/bjc/data/CircularIterator.java
+++ b/src/main/java/bjc/data/CircularIterator.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.Iterator;
diff --git a/src/main/java/bjc/data/Context.java b/src/main/java/bjc/data/Context.java
index 7efdc4d..f52160d 100644
--- a/src/main/java/bjc/data/Context.java
+++ b/src/main/java/bjc/data/Context.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 /**
diff --git a/src/main/java/bjc/data/Contexts.java b/src/main/java/bjc/data/Contexts.java
index f587fe6..699a450 100644
--- a/src/main/java/bjc/data/Contexts.java
+++ b/src/main/java/bjc/data/Contexts.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.*;
diff --git a/src/main/java/bjc/data/Either.java b/src/main/java/bjc/data/Either.java
index 90efba7..42d2e99 100644
--- a/src/main/java/bjc/data/Either.java
+++ b/src/main/java/bjc/data/Either.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.*;
diff --git a/src/main/java/bjc/data/GeneratingIterator.java b/src/main/java/bjc/data/GeneratingIterator.java
index 8900b94..5b46c4f 100644
--- a/src/main/java/bjc/data/GeneratingIterator.java
+++ b/src/main/java/bjc/data/GeneratingIterator.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.Iterator;
diff --git a/src/main/java/bjc/data/Holder.java b/src/main/java/bjc/data/Holder.java
index f01812e..4a1de75 100644
--- a/src/main/java/bjc/data/Holder.java
+++ b/src/main/java/bjc/data/Holder.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.function.Consumer;
diff --git a/src/main/java/bjc/data/Identity.java b/src/main/java/bjc/data/Identity.java
index fc4798e..174e2c9 100644
--- a/src/main/java/bjc/data/Identity.java
+++ b/src/main/java/bjc/data/Identity.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.function.Function;
diff --git a/src/main/java/bjc/data/IntHolder.java b/src/main/java/bjc/data/IntHolder.java
index 2783669..c5d088a 100644
--- a/src/main/java/bjc/data/IntHolder.java
+++ b/src/main/java/bjc/data/IntHolder.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 /**
diff --git a/src/main/java/bjc/data/Lazy.java b/src/main/java/bjc/data/Lazy.java
index b237935..45293e2 100644
--- a/src/main/java/bjc/data/Lazy.java
+++ b/src/main/java/bjc/data/Lazy.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.function.Function;
diff --git a/src/main/java/bjc/data/LazyPair.java b/src/main/java/bjc/data/LazyPair.java
index 048254a..b8297af 100644
--- a/src/main/java/bjc/data/LazyPair.java
+++ b/src/main/java/bjc/data/LazyPair.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.function.BiFunction;
diff --git a/src/main/java/bjc/data/ListHolder.java b/src/main/java/bjc/data/ListHolder.java
index c8a75ff..4e2594c 100644
--- a/src/main/java/bjc/data/ListHolder.java
+++ b/src/main/java/bjc/data/ListHolder.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.function.Function;
diff --git a/src/main/java/bjc/data/MarkListIterator.java b/src/main/java/bjc/data/MarkListIterator.java
index 35baa28..97f5641 100644
--- a/src/main/java/bjc/data/MarkListIterator.java
+++ b/src/main/java/bjc/data/MarkListIterator.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.*;
diff --git a/src/main/java/bjc/data/NonCMEIterator.java b/src/main/java/bjc/data/NonCMEIterator.java
index 88eaa6b..70cd2cf 100644
--- a/src/main/java/bjc/data/NonCMEIterator.java
+++ b/src/main/java/bjc/data/NonCMEIterator.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.*;
diff --git a/src/main/java/bjc/data/NonCMEListIterator.java b/src/main/java/bjc/data/NonCMEListIterator.java
index 6e74a24..bd22f6f 100644
--- a/src/main/java/bjc/data/NonCMEListIterator.java
+++ b/src/main/java/bjc/data/NonCMEListIterator.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.*;
diff --git a/src/main/java/bjc/data/OneWayToggle.java b/src/main/java/bjc/data/OneWayToggle.java
index b6074b0..0705344 100644
--- a/src/main/java/bjc/data/OneWayToggle.java
+++ b/src/main/java/bjc/data/OneWayToggle.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 /**
diff --git a/src/main/java/bjc/data/Option.java b/src/main/java/bjc/data/Option.java
index 6ca8b13..4118cc8 100644
--- a/src/main/java/bjc/data/Option.java
+++ b/src/main/java/bjc/data/Option.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.function.Function;
diff --git a/src/main/java/bjc/data/Pair.java b/src/main/java/bjc/data/Pair.java
index 1d4be5e..fe65936 100644
--- a/src/main/java/bjc/data/Pair.java
+++ b/src/main/java/bjc/data/Pair.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.Formattable;
diff --git a/src/main/java/bjc/data/PetriNet.java b/src/main/java/bjc/data/PetriNet.java
index 5fced8e..b4c08e1 100644
--- a/src/main/java/bjc/data/PetriNet.java
+++ b/src/main/java/bjc/data/PetriNet.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.*;
diff --git a/src/main/java/bjc/data/PetriTransition.java b/src/main/java/bjc/data/PetriTransition.java
index d1d20f9..79f879d 100644
--- a/src/main/java/bjc/data/PetriTransition.java
+++ b/src/main/java/bjc/data/PetriTransition.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.*;
diff --git a/src/main/java/bjc/data/QueuedIterator.java b/src/main/java/bjc/data/QueuedIterator.java
index 805fc5e..044bd65 100644
--- a/src/main/java/bjc/data/QueuedIterator.java
+++ b/src/main/java/bjc/data/QueuedIterator.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.ArrayDeque;
diff --git a/src/main/java/bjc/data/ResettableIterator.java b/src/main/java/bjc/data/ResettableIterator.java
index 8c1c4aa..29c56df 100644
--- a/src/main/java/bjc/data/ResettableIterator.java
+++ b/src/main/java/bjc/data/ResettableIterator.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.*;
diff --git a/src/main/java/bjc/data/ReverseListIterator.java b/src/main/java/bjc/data/ReverseListIterator.java
index 0b6ec84..273d4c7 100644
--- a/src/main/java/bjc/data/ReverseListIterator.java
+++ b/src/main/java/bjc/data/ReverseListIterator.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.*;
diff --git a/src/main/java/bjc/data/SimplePair.java b/src/main/java/bjc/data/SimplePair.java
index 48f5ca3..e5de68f 100644
--- a/src/main/java/bjc/data/SimplePair.java
+++ b/src/main/java/bjc/data/SimplePair.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.function.BiFunction;
diff --git a/src/main/java/bjc/data/SimpleTree.java b/src/main/java/bjc/data/SimpleTree.java
index 7d9fb6d..826b1b3 100644
--- a/src/main/java/bjc/data/SimpleTree.java
+++ b/src/main/java/bjc/data/SimpleTree.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.function.BiFunction;
diff --git a/src/main/java/bjc/data/SingleIterator.java b/src/main/java/bjc/data/SingleIterator.java
index 1598774..19b9d90 100644
--- a/src/main/java/bjc/data/SingleIterator.java
+++ b/src/main/java/bjc/data/SingleIterator.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.Iterator;
diff --git a/src/main/java/bjc/data/SingleSupplier.java b/src/main/java/bjc/data/SingleSupplier.java
index 010b06e..1b020a4 100644
--- a/src/main/java/bjc/data/SingleSupplier.java
+++ b/src/main/java/bjc/data/SingleSupplier.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.function.Supplier;
diff --git a/src/main/java/bjc/data/Toggle.java b/src/main/java/bjc/data/Toggle.java
index 17c5a8e..6351858 100644
--- a/src/main/java/bjc/data/Toggle.java
+++ b/src/main/java/bjc/data/Toggle.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 /**
diff --git a/src/main/java/bjc/data/TopDownTransformIterator.java b/src/main/java/bjc/data/TopDownTransformIterator.java
index 28df590..33d4718 100644
--- a/src/main/java/bjc/data/TopDownTransformIterator.java
+++ b/src/main/java/bjc/data/TopDownTransformIterator.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import static bjc.data.TopDownTransformResult.RTRANSFORM;
diff --git a/src/main/java/bjc/data/TopDownTransformResult.java b/src/main/java/bjc/data/TopDownTransformResult.java
index 0633cec..61f1a4d 100644
--- a/src/main/java/bjc/data/TopDownTransformResult.java
+++ b/src/main/java/bjc/data/TopDownTransformResult.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 /**
diff --git a/src/main/java/bjc/data/TransformIterator.java b/src/main/java/bjc/data/TransformIterator.java
index 29f91e2..35b448f 100644
--- a/src/main/java/bjc/data/TransformIterator.java
+++ b/src/main/java/bjc/data/TransformIterator.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.Iterator;
diff --git a/src/main/java/bjc/data/Tree.java b/src/main/java/bjc/data/Tree.java
index 784bf0e..039a813 100644
--- a/src/main/java/bjc/data/Tree.java
+++ b/src/main/java/bjc/data/Tree.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 import java.util.function.BiFunction;
diff --git a/src/main/java/bjc/data/ValueToggle.java b/src/main/java/bjc/data/ValueToggle.java
index 9e4b83b..4e9f7c0 100644
--- a/src/main/java/bjc/data/ValueToggle.java
+++ b/src/main/java/bjc/data/ValueToggle.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data;
 
 /**
diff --git a/src/main/java/bjc/data/internals/BoundLazy.java b/src/main/java/bjc/data/internals/BoundLazy.java
index 0e0e95c..115abd8 100644
--- a/src/main/java/bjc/data/internals/BoundLazy.java
+++ b/src/main/java/bjc/data/internals/BoundLazy.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data.internals;
 
 import java.util.function.Function;
diff --git a/src/main/java/bjc/data/internals/BoundLazyPair.java b/src/main/java/bjc/data/internals/BoundLazyPair.java
index 91981de..432ebdc 100644
--- a/src/main/java/bjc/data/internals/BoundLazyPair.java
+++ b/src/main/java/bjc/data/internals/BoundLazyPair.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data.internals;
 
 import java.util.function.BiFunction;
diff --git a/src/main/java/bjc/data/internals/BoundListHolder.java b/src/main/java/bjc/data/internals/BoundListHolder.java
index c944252..3af5720 100644
--- a/src/main/java/bjc/data/internals/BoundListHolder.java
+++ b/src/main/java/bjc/data/internals/BoundListHolder.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data.internals;
 
 import java.util.function.Function;
diff --git a/src/main/java/bjc/data/internals/HalfBoundLazyPair.java b/src/main/java/bjc/data/internals/HalfBoundLazyPair.java
index 849b973..b59ac68 100644
--- a/src/main/java/bjc/data/internals/HalfBoundLazyPair.java
+++ b/src/main/java/bjc/data/internals/HalfBoundLazyPair.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data.internals;
 
 import java.util.function.BiFunction;
diff --git a/src/main/java/bjc/data/internals/WrappedLazy.java b/src/main/java/bjc/data/internals/WrappedLazy.java
index 624fb1b..138991a 100644
--- a/src/main/java/bjc/data/internals/WrappedLazy.java
+++ b/src/main/java/bjc/data/internals/WrappedLazy.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data.internals;
 
 import java.util.function.Function;
diff --git a/src/main/java/bjc/data/internals/WrappedOption.java b/src/main/java/bjc/data/internals/WrappedOption.java
index f46d501..b71e150 100644
--- a/src/main/java/bjc/data/internals/WrappedOption.java
+++ b/src/main/java/bjc/data/internals/WrappedOption.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.data.internals;
 
 import java.util.function.Function;
diff --git a/src/main/java/bjc/esodata/AbbrevMap2.java b/src/main/java/bjc/esodata/AbbrevMap2.java
index 341a28d..72bd4c8 100644
--- a/src/main/java/bjc/esodata/AbbrevMap2.java
+++ b/src/main/java/bjc/esodata/AbbrevMap2.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.*;
@@ -25,7 +42,7 @@ public class AbbrevMap2 {
 	 * Create a new abbreviation map.
 	 */
 	public AbbrevMap2() {
-		backing = new Multimap<>();
+		backing = new TSetMultimap<>();
 	}
 
 	/**
diff --git a/src/main/java/bjc/esodata/AbbrevTree.java b/src/main/java/bjc/esodata/AbbrevTree.java
index 35c44f0..c2ad8db 100644
--- a/src/main/java/bjc/esodata/AbbrevTree.java
+++ b/src/main/java/bjc/esodata/AbbrevTree.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.*;
@@ -22,7 +39,7 @@ import bjc.funcdata.ListEx;
  * @param <Contained> The type of data contained in the nodes.
  */
 public class AbbrevTree<Label, Contained> implements Iterable<Pair<Label, Contained>> {
-	private Multimap<Label, AbbrevTree<Label, Contained>> labelledNodes;
+	private TSetMultimap<Label, AbbrevTree<Label, Contained>> labelledNodes;
 
 	private Map<Label, AbbrevTree<Label, Contained>> children;
 	private AbbrevTree<Label, Contained> parent;
@@ -34,7 +51,7 @@ public class AbbrevTree<Label, Contained> implements Iterable<Pair<Label, Contai
 	 * Create a new empty root AbbrevTree.
 	 */
 	public AbbrevTree() {
-		labelledNodes = new Multimap<>();
+		labelledNodes = new TSetMultimap<>();
 		children = new HashMap<>();
 	}
 
@@ -57,7 +74,7 @@ public class AbbrevTree<Label, Contained> implements Iterable<Pair<Label, Contai
 	 * @param parent The parent of this node
 	 */
 	public AbbrevTree(AbbrevTree<Label, Contained> parent) {
-		labelledNodes = new Multimap<>();
+		labelledNodes = new TSetMultimap<>();
 		children = new HashMap<>();
 
 		this.parent = parent;
diff --git a/src/main/java/bjc/esodata/DefaultList.java b/src/main/java/bjc/esodata/DefaultList.java
index e622301..727eafd 100644
--- a/src/main/java/bjc/esodata/DefaultList.java
+++ b/src/main/java/bjc/esodata/DefaultList.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.AbstractList;
diff --git a/src/main/java/bjc/esodata/Directory.java b/src/main/java/bjc/esodata/Directory.java
index fa47b6f..feeb25c 100644
--- a/src/main/java/bjc/esodata/Directory.java
+++ b/src/main/java/bjc/esodata/Directory.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 /**
diff --git a/src/main/java/bjc/esodata/DoubleSided.java b/src/main/java/bjc/esodata/DoubleSided.java
index 8ac6684..0ec417a 100644
--- a/src/main/java/bjc/esodata/DoubleSided.java
+++ b/src/main/java/bjc/esodata/DoubleSided.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 /**
diff --git a/src/main/java/bjc/esodata/DoubleTape.java b/src/main/java/bjc/esodata/DoubleTape.java
index 30d94a1..e7ba98c 100644
--- a/src/main/java/bjc/esodata/DoubleTape.java
+++ b/src/main/java/bjc/esodata/DoubleTape.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 /**
diff --git a/src/main/java/bjc/esodata/FlatNestIterator.java b/src/main/java/bjc/esodata/FlatNestIterator.java
index 42981f5..60463d8 100644
--- a/src/main/java/bjc/esodata/FlatNestIterator.java
+++ b/src/main/java/bjc/esodata/FlatNestIterator.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.*;
diff --git a/src/main/java/bjc/esodata/KeyedList.java b/src/main/java/bjc/esodata/KeyedList.java
new file mode 100644
index 0000000..5b0d6cc
--- /dev/null
+++ b/src/main/java/bjc/esodata/KeyedList.java
@@ -0,0 +1,123 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package bjc.esodata;
+
+import java.util.*;
+
+public class KeyedList<Key, Val> implements Iterable<Val> {
+	private List<Val> backing;
+	private Map<Key, Integer> indices;
+
+	private int currIdx = 0;
+
+	public KeyedList() {
+		backing = new ArrayList<>();
+		indices = new HashMap<>();
+	}
+
+	/**
+	 * Add a item to this list.
+	 * 
+	 * If an item already exists with the given key, the current one will not be
+	 * added. Use <code>set</code> to handle that.
+	 * 
+	 * @param key The key for this item.
+	 * @param val The value for this item
+	 * 
+	 * @return Whether or not this item was added to the list
+	 */
+	public boolean add(Key key, Val val) {
+		// TODO: Determine if this is the desired behavior
+		if (indices.containsKey(key))
+			return false;
+
+		backing.add(val);
+		indices.put(key, currIdx++);
+		return true;
+	}
+
+	/**
+	 * Set the item associated with a given key.
+	 * 
+	 * @param key    The key to set
+	 * @param newVal The new value for the key
+	 * 
+	 * @return The previous value for the key, if there was one
+	 */
+	public Val set(Key key, Val newVal) {
+		if (indices.containsKey(key)) {
+			return backing.set(indices.get(key), newVal);
+		}
+
+		add(key, newVal);
+		return null;
+	}
+
+	/**
+	 * Retrieve all of the keys for this list.
+	 * 
+	 * @return An immutable set of the keys for this list
+	 */
+	public Set<Key> keys() {
+		// TODO: write mutable wrapper which will update the list appropriately
+		return Collections.unmodifiableSet(indices.keySet());
+	}
+
+	/**
+	 * Retrieve the value associated with the given key.
+	 * 
+	 * @param key The key to look up.
+	 * 
+	 * @return The value for the given key.
+	 */
+	public Val get(Key key) {
+		return backing.get(indices.get(key));
+	}
+
+	/**
+	 * Check if this list contains a value for a given key.
+	 * 
+	 * @param key The key to look up.
+	 * 
+	 * @return Whether this list contains a value for the given key.
+	 */
+	public boolean containsKey(Key key) {
+		return indices.containsKey(key);
+	}
+
+	@Override
+	public Iterator<Val> iterator() {
+		return backing.iterator();
+	}
+
+	/**
+	 * Return an iterator that starts at the value for the given key.'
+	 * 
+	 * @param key The key to start at.
+	 * 
+	 * @return An iterator starting at the given key, or null if the key isn't
+	 *         present.
+	 */
+	public ListIterator<Val> iteratorFrom(Key key) {
+		if (indices.containsKey(key)) {
+			return backing.listIterator(indices.get(key));
+		}
+
+		return null;
+	}
+}
diff --git a/src/main/java/bjc/esodata/MapSet.java b/src/main/java/bjc/esodata/MapSet.java
index 7d77ad6..ade6219 100644
--- a/src/main/java/bjc/esodata/MapSet.java
+++ b/src/main/java/bjc/esodata/MapSet.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.AbstractMap;
diff --git a/src/main/java/bjc/esodata/MinMaxList.java b/src/main/java/bjc/esodata/MinMaxList.java
index 6747831..50b0ea0 100644
--- a/src/main/java/bjc/esodata/MinMaxList.java
+++ b/src/main/java/bjc/esodata/MinMaxList.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.*;
diff --git a/src/main/java/bjc/esodata/Multimap.java b/src/main/java/bjc/esodata/Multimap.java
index e18ed49..d0c0b4b 100644
--- a/src/main/java/bjc/esodata/Multimap.java
+++ b/src/main/java/bjc/esodata/Multimap.java
@@ -1,153 +1,102 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.*;
-import java.util.Map.Entry;
 
 import bjc.data.Pair;
 
 /**
- * A map that has support for multiple values for a given key.
- *
- * Whenever you give another value for a key, that is then returned for that
- * key. About the only somewhat complex thing, is that, if you add the same
- * key-value pair multiple times, it will only show up once. However, you will
- * have to remove that pair as many times as you added it.
+ * A map that supports multiple values for a given key.
+ * 
+ * The thing that will tend to vary with the implementation is what they do with
+ * duplicate values for the same key.
+ * 
+ * @author bjcul
  *
- * @author Ben Culkin
- * @param <KeyType> The type of keys in the map.
- * @param <ValueType> The type of values in the map.
+ * @param <KeyType> The key type of the map
+ * @param <ValueType> The value type of the map.
  */
-public class Multimap<KeyType, ValueType> implements Iterable<Pair<KeyType, ValueType>> {
-	private Map<KeyType, ThresholdSet<ValueType>> backing;
-
-	/**
-	 * Create a new empty multimap.
-	 */
-	public Multimap() {
-		backing = new HashMap<>();
-	}
-
+public interface Multimap<KeyType, ValueType> {
 	/**
 	 * Add a key-value mapping to the map.
 	 *
-	 * @param key
-	 *              The key to store the value under.
+	 * @param key   The key to store the value under.
 	 *
-	 * @param value
-	 *              The value to store.
+	 * @param value The value to store.
 	 */
-	public void add(KeyType key, ValueType value) {
-		ThresholdSet<ValueType> container
-				= backing.computeIfAbsent(key, k -> new ThresholdSet<>());
-
-		container.add(value);
-	}
+	void add(KeyType key, ValueType value);
 
 	/**
 	 * Delete a particular key-value mapping from the map.
 	 *
-	 * @param key
-	 *              The key of the mapping to remove.
+	 * @param key   The key of the mapping to remove.
 	 *
-	 * @param value
-	 *              The value of the mapping to remove.
+	 * @param value The value of the mapping to remove.
 	 */
-	public void remove(KeyType key, ValueType value) {
-		// We have no values for that key; bail.
-		if (!backing.containsKey(key)) return;
-		
-		backing.get(key).remove(value);
-	}
+	void remove(KeyType key, ValueType value);
 
 	/**
 	 * Delete all of the values associated with a particular key.
 	 *
-	 * @param key
-	 *            The key to remove values for.
+	 * @param key The key to remove values for.
 	 */
-	public void remove(KeyType key) {
-		backing.remove(key);
-	}
+	void remove(KeyType key);
 
 	/**
 	 * Get a set containing all of the values that are recorded for that key.
 	 *
-	 * @param key
-	 *            The key to look up values for.
+	 * @param key The key to look up values for.
 	 *
 	 * @return A set containing all of the values that have been mapped to that key.
 	 */
-	public Set<ValueType> get(KeyType key) {
-		if (!backing.containsKey(key)) return new HashSet<>();
-		else                           return backing.get(key).values();
-	}
+	Set<ValueType> get(KeyType key);
 
 	/**
 	 * Get the single value in the map, if there is one.
+	 * 
 	 * @param key The key to look up
-	 * @return An optional containing the key if it is there once, or empty if it is there either no or more than one times
+	 * @return An optional containing the key if it is there once, or empty if it is
+	 *         there either no or more than one times
 	 */
-	public Optional<ValueType> getSingle(KeyType key) {
-		Set<ValueType> set = get(key);
-		
-		if (set.size() == 1) return Optional.of(set.iterator().next());
-		return Optional.empty();
-	}
+	Optional<ValueType> getSingle(KeyType key);
+
 	/**
 	 * Check if there is at least one value mapped to the given key.
 	 *
-	 * @param key
-	 *            The key to check for mappings for.
+	 * @param key The key to check for mappings for.
 	 *
 	 * @return Whether or not there is at least one value mapped to the key.
 	 */
-	public boolean contains(KeyType key) {
-		return backing.containsKey(key);
-	}
+	boolean contains(KeyType key);
 
 	/**
 	 * Check if there is at least one instance of a particular key-value mapping.
 	 *
-	 * @param key
-	 *              The key to check for mappings for.
+	 * @param key   The key to check for mappings for.
 	 *
-	 * @param value
-	 *              The value to check for mappings for.
+	 * @param value The value to check for mappings for.
 	 *
 	 * @return Whether or not there is at least one instance of the given key-value
 	 *         mapping.
 	 */
-	public boolean contains(KeyType key, ValueType value) {
-		if (!backing.containsKey(key)) return false;
+	boolean contains(KeyType key, ValueType value);
+
+	Iterator<Pair<KeyType, ValueType>> iterator();
 
-		return backing.get(key).contains(value) > 0;
-	}
-	
-	@Override
-	public Iterator<Pair<KeyType, ValueType>> iterator() {
-		return new Iterator<>() {
-			private Iterator<Entry<KeyType, ThresholdSet<ValueType>>> mapIter = backing.entrySet().iterator();
-			private KeyType currKey;
-			private Iterator<ValueType> setIter;
-			
-			@Override
-			public boolean hasNext() {
-				while (setIter == null || !setIter.hasNext()) {
-					if (!mapIter.hasNext()) return false;
-					Entry<KeyType,ThresholdSet<ValueType>> entry = mapIter.next();
-					
-					currKey = entry.getKey();
-					setIter = entry.getValue().setView().iterator();
-				}
-				
-				return setIter.hasNext();
-			}
-			
-			@Override
-			public Pair<KeyType, ValueType> next() {
-				if (setIter == null || !setIter.hasNext()) throw new NoSuchElementException();
-				return Pair.pair(currKey, setIter.next()) ;
-			}
-		};
-	}
-}
+}
\ No newline at end of file
diff --git a/src/main/java/bjc/esodata/NestList.java b/src/main/java/bjc/esodata/NestList.java
index 9d9149c..c1544ca 100644
--- a/src/main/java/bjc/esodata/NestList.java
+++ b/src/main/java/bjc/esodata/NestList.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import static bjc.functypes.Combinators.*;
diff --git a/src/main/java/bjc/esodata/PairMap.java b/src/main/java/bjc/esodata/PairMap.java
index ba13a2f..0e01bd3 100644
--- a/src/main/java/bjc/esodata/PairMap.java
+++ b/src/main/java/bjc/esodata/PairMap.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.*;
@@ -29,8 +46,8 @@ public class PairMap<Left, Right, Value> implements Map<Pair<Left, Right>, Value
 	public PairMap() {
 		this.backing = new HashMap<>();
 		
-		this.leftTracker = new Multimap<>();
-		this.rightTracker = new Multimap<>();
+		this.leftTracker = new TSetMultimap<>();
+		this.rightTracker = new TSetMultimap<>();
 	}
 	
 	/**
@@ -122,8 +139,8 @@ public class PairMap<Left, Right, Value> implements Map<Pair<Left, Right>, Value
 	public void clear() {
 		backing.clear();
 
-		leftTracker = new Multimap<>();
-		rightTracker = new Multimap<>();
+		leftTracker = new TSetMultimap<>();
+		rightTracker = new TSetMultimap<>();
 	}
 
 	// TODO: Update these to not break the tracking invariants
diff --git a/src/main/java/bjc/esodata/PushdownMap.java b/src/main/java/bjc/esodata/PushdownMap.java
index 76dd2db..a6e153c 100644
--- a/src/main/java/bjc/esodata/PushdownMap.java
+++ b/src/main/java/bjc/esodata/PushdownMap.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.*;
diff --git a/src/main/java/bjc/esodata/QueueStack.java b/src/main/java/bjc/esodata/QueueStack.java
index e310f16..22b849a 100644
--- a/src/main/java/bjc/esodata/QueueStack.java
+++ b/src/main/java/bjc/esodata/QueueStack.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.Deque;
diff --git a/src/main/java/bjc/esodata/SimpleDirectory.java b/src/main/java/bjc/esodata/SimpleDirectory.java
index 13a9f3e..4cc6f35 100644
--- a/src/main/java/bjc/esodata/SimpleDirectory.java
+++ b/src/main/java/bjc/esodata/SimpleDirectory.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import bjc.funcdata.FunctionalMap;
diff --git a/src/main/java/bjc/esodata/SimpleStack.java b/src/main/java/bjc/esodata/SimpleStack.java
index 9c016c3..55d4000 100644
--- a/src/main/java/bjc/esodata/SimpleStack.java
+++ b/src/main/java/bjc/esodata/SimpleStack.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.Deque;
diff --git a/src/main/java/bjc/esodata/SingleTape.java b/src/main/java/bjc/esodata/SingleTape.java
index 7c3a34f..ff34178 100644
--- a/src/main/java/bjc/esodata/SingleTape.java
+++ b/src/main/java/bjc/esodata/SingleTape.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.ArrayList;
diff --git a/src/main/java/bjc/esodata/SpaghettiStack.java b/src/main/java/bjc/esodata/SpaghettiStack.java
index 4bd77d3..ab57646 100644
--- a/src/main/java/bjc/esodata/SpaghettiStack.java
+++ b/src/main/java/bjc/esodata/SpaghettiStack.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.Arrays;
diff --git a/src/main/java/bjc/esodata/Stack.java b/src/main/java/bjc/esodata/Stack.java
index 9dfee17..6027a23 100644
--- a/src/main/java/bjc/esodata/Stack.java
+++ b/src/main/java/bjc/esodata/Stack.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.*;
diff --git a/src/main/java/bjc/esodata/TSetMultimap.java b/src/main/java/bjc/esodata/TSetMultimap.java
new file mode 100644
index 0000000..1a04a41
--- /dev/null
+++ b/src/main/java/bjc/esodata/TSetMultimap.java
@@ -0,0 +1,124 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package bjc.esodata;
+
+import java.util.*;
+import java.util.Map.Entry;
+
+import bjc.data.Pair;
+
+/**
+ * A map that has support for multiple values for a given key.
+ *
+ * Whenever you give another value for a key, that is then returned for that
+ * key. About the only somewhat complex thing, is that, if you add the same
+ * key-value pair multiple times, it will only show up once. However, you will
+ * have to remove that pair as many times as you added it.
+ *
+ * @author Ben Culkin
+ * 
+ * @param <KeyType> The type of keys in the map.
+ * @param <ValueType> The type of values in the map.
+ */
+public class TSetMultimap<KeyType, ValueType> implements Iterable<Pair<KeyType, ValueType>>, Multimap<KeyType, ValueType> {
+	private final class SetMultimapIterator implements Iterator<Pair<KeyType, ValueType>> {
+		private Iterator<Entry<KeyType, ThresholdSet<ValueType>>> mapIter = backing.entrySet().iterator();
+		private KeyType currKey;
+		private Iterator<ValueType> setIter;
+
+		@Override
+		public boolean hasNext() {
+			while (setIter == null || !setIter.hasNext()) {
+				if (!mapIter.hasNext()) return false;
+				Entry<KeyType,ThresholdSet<ValueType>> entry = mapIter.next();
+				
+				currKey = entry.getKey();
+				setIter = entry.getValue().setView().iterator();
+			}
+			
+			return setIter.hasNext();
+		}
+
+		@Override
+		public Pair<KeyType, ValueType> next() {
+			if (setIter == null || !setIter.hasNext()) throw new NoSuchElementException();
+			return Pair.pair(currKey, setIter.next()) ;
+		}
+	}
+
+	private Map<KeyType, ThresholdSet<ValueType>> backing;
+
+	/**
+	 * Create a new empty multimap.
+	 */
+	public TSetMultimap() {
+		backing = new HashMap<>();
+	}
+
+	@Override
+	public void add(KeyType key, ValueType value) {
+		ThresholdSet<ValueType> container
+				= backing.computeIfAbsent(key, k -> new ThresholdSet<>());
+
+		container.add(value);
+	}
+
+	@Override
+	public void remove(KeyType key, ValueType value) {
+		// We have no values for that key; bail.
+		if (!backing.containsKey(key)) return;
+		
+		backing.get(key).remove(value);
+	}
+
+	@Override
+	public void remove(KeyType key) {
+		backing.remove(key);
+	}
+
+	@Override
+	public Set<ValueType> get(KeyType key) {
+		if (!backing.containsKey(key)) return new HashSet<>();
+		else                           return backing.get(key).values();
+	}
+
+	@Override
+	public Optional<ValueType> getSingle(KeyType key) {
+		Set<ValueType> set = get(key);
+		
+		if (set.size() == 1) return Optional.of(set.iterator().next());
+		return Optional.empty();
+	}
+
+	@Override
+	public boolean contains(KeyType key) {
+		return backing.containsKey(key);
+	}
+
+	@Override
+	public boolean contains(KeyType key, ValueType value) {
+		if (!backing.containsKey(key)) return false;
+
+		return backing.get(key).contains(value) > 0;
+	}
+	
+	@Override
+	public Iterator<Pair<KeyType, ValueType>> iterator() {
+		return new SetMultimapIterator();
+	}
+}
diff --git a/src/main/java/bjc/esodata/Tape.java b/src/main/java/bjc/esodata/Tape.java
index 134ba62..efc3df7 100644
--- a/src/main/java/bjc/esodata/Tape.java
+++ b/src/main/java/bjc/esodata/Tape.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 /**
diff --git a/src/main/java/bjc/esodata/TapeLibrary.java b/src/main/java/bjc/esodata/TapeLibrary.java
index 922833f..5fec28a 100644
--- a/src/main/java/bjc/esodata/TapeLibrary.java
+++ b/src/main/java/bjc/esodata/TapeLibrary.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.*;
diff --git a/src/main/java/bjc/esodata/TapeView.java b/src/main/java/bjc/esodata/TapeView.java
index bfc33a9..94192d8 100644
--- a/src/main/java/bjc/esodata/TapeView.java
+++ b/src/main/java/bjc/esodata/TapeView.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 /**
diff --git a/src/main/java/bjc/esodata/ThresholdSet.java b/src/main/java/bjc/esodata/ThresholdSet.java
index c13bad3..645d4d3 100644
--- a/src/main/java/bjc/esodata/ThresholdSet.java
+++ b/src/main/java/bjc/esodata/ThresholdSet.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import java.util.*;
diff --git a/src/main/java/bjc/esodata/UnifiedDirectory.java b/src/main/java/bjc/esodata/UnifiedDirectory.java
index 1b630eb..3b521c0 100644
--- a/src/main/java/bjc/esodata/UnifiedDirectory.java
+++ b/src/main/java/bjc/esodata/UnifiedDirectory.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata;
 
 import bjc.funcdata.FunctionalMap;
diff --git a/src/main/java/bjc/esodata/spool/Spool.java b/src/main/java/bjc/esodata/spool/Spool.java
index dbd2ce8..80e8a8c 100644
--- a/src/main/java/bjc/esodata/spool/Spool.java
+++ b/src/main/java/bjc/esodata/spool/Spool.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata.spool;
 
 public interface Spool<Contained> {
diff --git a/src/main/java/bjc/esodata/spool/Spooler.java b/src/main/java/bjc/esodata/spool/Spooler.java
index a222a25..133df2e 100644
--- a/src/main/java/bjc/esodata/spool/Spooler.java
+++ b/src/main/java/bjc/esodata/spool/Spooler.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.esodata.spool;
 
 public interface Spooler {
diff --git a/src/main/java/bjc/funcdata/CList.java b/src/main/java/bjc/funcdata/CList.java
index b9ee10e..4995b61 100644
--- a/src/main/java/bjc/funcdata/CList.java
+++ b/src/main/java/bjc/funcdata/CList.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata;
 
 import java.util.function.UnaryOperator;
diff --git a/src/main/java/bjc/funcdata/CListLike.java b/src/main/java/bjc/funcdata/CListLike.java
index ba17456..9742fc5 100644
--- a/src/main/java/bjc/funcdata/CListLike.java
+++ b/src/main/java/bjc/funcdata/CListLike.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata;
 
 public interface CListLike<T> {
diff --git a/src/main/java/bjc/funcdata/CListStructure.java b/src/main/java/bjc/funcdata/CListStructure.java
index 1809273..390a47e 100644
--- a/src/main/java/bjc/funcdata/CListStructure.java
+++ b/src/main/java/bjc/funcdata/CListStructure.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata;
 
 import bjc.data.Either;
diff --git a/src/main/java/bjc/funcdata/ExtendedMap.java b/src/main/java/bjc/funcdata/ExtendedMap.java
index 379ff65..4bee343 100644
--- a/src/main/java/bjc/funcdata/ExtendedMap.java
+++ b/src/main/java/bjc/funcdata/ExtendedMap.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata;
 
 import java.util.*;
diff --git a/src/main/java/bjc/funcdata/Freezable.java b/src/main/java/bjc/funcdata/Freezable.java
index 8bb037c..c337509 100644
--- a/src/main/java/bjc/funcdata/Freezable.java
+++ b/src/main/java/bjc/funcdata/Freezable.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata;
 
 /**
diff --git a/src/main/java/bjc/funcdata/FunctionalList.java b/src/main/java/bjc/funcdata/FunctionalList.java
index c9c3a9f..ae7ae3a 100644
--- a/src/main/java/bjc/funcdata/FunctionalList.java
+++ b/src/main/java/bjc/funcdata/FunctionalList.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata;
 
 import java.util.ArrayList;
diff --git a/src/main/java/bjc/funcdata/FunctionalMap.java b/src/main/java/bjc/funcdata/FunctionalMap.java
index 3427a91..33a97e6 100644
--- a/src/main/java/bjc/funcdata/FunctionalMap.java
+++ b/src/main/java/bjc/funcdata/FunctionalMap.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata;
 
 import java.util.*;
diff --git a/src/main/java/bjc/funcdata/FunctionalStringTokenizer.java b/src/main/java/bjc/funcdata/FunctionalStringTokenizer.java
index 3344e05..211be85 100644
--- a/src/main/java/bjc/funcdata/FunctionalStringTokenizer.java
+++ b/src/main/java/bjc/funcdata/FunctionalStringTokenizer.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata;
 
 import java.util.StringTokenizer;
diff --git a/src/main/java/bjc/funcdata/ListEx.java b/src/main/java/bjc/funcdata/ListEx.java
index 164a71d..fd947cf 100644
--- a/src/main/java/bjc/funcdata/ListEx.java
+++ b/src/main/java/bjc/funcdata/ListEx.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata;
 
 import java.util.Comparator;
diff --git a/src/main/java/bjc/funcdata/MapEx.java b/src/main/java/bjc/funcdata/MapEx.java
index a7af4c5..1dad1dc 100644
--- a/src/main/java/bjc/funcdata/MapEx.java
+++ b/src/main/java/bjc/funcdata/MapEx.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata;
 
 import java.util.*;
diff --git a/src/main/java/bjc/funcdata/ObjectFrozen.java b/src/main/java/bjc/funcdata/ObjectFrozen.java
index a9f58b8..2951ec3 100644
--- a/src/main/java/bjc/funcdata/ObjectFrozen.java
+++ b/src/main/java/bjc/funcdata/ObjectFrozen.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata;
 
 /**
diff --git a/src/main/java/bjc/funcdata/SentryList.java b/src/main/java/bjc/funcdata/SentryList.java
index b0554f5..e890370 100644
--- a/src/main/java/bjc/funcdata/SentryList.java
+++ b/src/main/java/bjc/funcdata/SentryList.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata;
 
 import java.util.List;
diff --git a/src/main/java/bjc/funcdata/TransformedValueMap.java b/src/main/java/bjc/funcdata/TransformedValueMap.java
index 643f610..57fe155 100644
--- a/src/main/java/bjc/funcdata/TransformedValueMap.java
+++ b/src/main/java/bjc/funcdata/TransformedValueMap.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata;
 
 import java.util.*;
diff --git a/src/main/java/bjc/funcdata/bst/BinarySearchTree.java b/src/main/java/bjc/funcdata/bst/BinarySearchTree.java
index 99b67cd..7cec49a 100644
--- a/src/main/java/bjc/funcdata/bst/BinarySearchTree.java
+++ b/src/main/java/bjc/funcdata/bst/BinarySearchTree.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata.bst;
 
 import java.util.ArrayList;
diff --git a/src/main/java/bjc/funcdata/bst/BinarySearchTreeLeaf.java b/src/main/java/bjc/funcdata/bst/BinarySearchTreeLeaf.java
index 9532555..fe9ad00 100644
--- a/src/main/java/bjc/funcdata/bst/BinarySearchTreeLeaf.java
+++ b/src/main/java/bjc/funcdata/bst/BinarySearchTreeLeaf.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata.bst;
 
 import java.util.Comparator;
diff --git a/src/main/java/bjc/funcdata/bst/BinarySearchTreeNode.java b/src/main/java/bjc/funcdata/bst/BinarySearchTreeNode.java
index 0eef92a..12ed209 100644
--- a/src/main/java/bjc/funcdata/bst/BinarySearchTreeNode.java
+++ b/src/main/java/bjc/funcdata/bst/BinarySearchTreeNode.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata.bst;
 
 import static bjc.funcdata.bst.DirectedWalkFunction.DirectedWalkResult.FAILURE;
diff --git a/src/main/java/bjc/funcdata/bst/DirectedWalkFunction.java b/src/main/java/bjc/funcdata/bst/DirectedWalkFunction.java
index 4f64339..b0cb76f 100644
--- a/src/main/java/bjc/funcdata/bst/DirectedWalkFunction.java
+++ b/src/main/java/bjc/funcdata/bst/DirectedWalkFunction.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata.bst;
 
 /**
diff --git a/src/main/java/bjc/funcdata/bst/TreeLinearizationMethod.java b/src/main/java/bjc/funcdata/bst/TreeLinearizationMethod.java
index 666834f..973a8dd 100644
--- a/src/main/java/bjc/funcdata/bst/TreeLinearizationMethod.java
+++ b/src/main/java/bjc/funcdata/bst/TreeLinearizationMethod.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata.bst;
 
 /**
diff --git a/src/main/java/bjc/funcdata/bst/TreePart.java b/src/main/java/bjc/funcdata/bst/TreePart.java
index b451463..999b5ca 100644
--- a/src/main/java/bjc/funcdata/bst/TreePart.java
+++ b/src/main/java/bjc/funcdata/bst/TreePart.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata.bst;
 
 import java.util.Comparator;
diff --git a/src/main/java/bjc/funcdata/theory/Bifunctor.java b/src/main/java/bjc/funcdata/theory/Bifunctor.java
index 72fccff..164a832 100644
--- a/src/main/java/bjc/funcdata/theory/Bifunctor.java
+++ b/src/main/java/bjc/funcdata/theory/Bifunctor.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata.theory;
 
 import java.util.function.Function;
diff --git a/src/main/java/bjc/funcdata/theory/Category.java b/src/main/java/bjc/funcdata/theory/Category.java
index 730465d..b5d8ee4 100644
--- a/src/main/java/bjc/funcdata/theory/Category.java
+++ b/src/main/java/bjc/funcdata/theory/Category.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata.theory;
 
 import java.util.Set;
diff --git a/src/main/java/bjc/funcdata/theory/Functor.java b/src/main/java/bjc/funcdata/theory/Functor.java
index 85a1ec7..7007325 100644
--- a/src/main/java/bjc/funcdata/theory/Functor.java
+++ b/src/main/java/bjc/funcdata/theory/Functor.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.funcdata.theory;
 
 import java.util.function.Function;
diff --git a/src/main/java/bjc/functypes/ArrayChooser.java b/src/main/java/bjc/functypes/ArrayChooser.java
index 3baa00c..d8619c5 100644
--- a/src/main/java/bjc/functypes/ArrayChooser.java
+++ b/src/main/java/bjc/functypes/ArrayChooser.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 /**
diff --git a/src/main/java/bjc/functypes/BiContainer.java b/src/main/java/bjc/functypes/BiContainer.java
new file mode 100644
index 0000000..db822ba
--- /dev/null
+++ b/src/main/java/bjc/functypes/BiContainer.java
@@ -0,0 +1,22 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package bjc.functypes;
+
+public interface BiContainer<L, R, C extends BiContainer<?, ?, C>> {
+	// marker
+}
diff --git a/src/main/java/bjc/functypes/CombinatorBirds.java b/src/main/java/bjc/functypes/CombinatorBirds.java
index d939a5b..55a53dd 100644
--- a/src/main/java/bjc/functypes/CombinatorBirds.java
+++ b/src/main/java/bjc/functypes/CombinatorBirds.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 import java.util.function.*;
diff --git a/src/main/java/bjc/functypes/Combinators.java b/src/main/java/bjc/functypes/Combinators.java
index 416230b..0b157bb 100644
--- a/src/main/java/bjc/functypes/Combinators.java
+++ b/src/main/java/bjc/functypes/Combinators.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 import static java.util.stream.Collectors.*;
@@ -281,11 +298,16 @@ public class Combinators {
 	public static <Input> Consumer<Input> ignore(Function<Input, ?> func) {
 		return (inp) -> func.apply(inp);
 	}
+
+	// TODO: write a switch-like combinator that uses a KeyedList to get the desired
+	// fallthrough semantics
+	
+	// TODO: non-shortcircuiting boolean combinators
 	
 	public static <Input, Output> Function<Supplier<Input>, Output> lazify(Function<Input, Output> f) {
 		return (supp) -> f.apply(supp.get());
 	}
-	
+
 	public static <Input, Output> Function<Input, Output> strictify(Function<Supplier<Input>, Output> f) {
 		return (val) -> f.apply(() -> val);
 	}
diff --git a/src/main/java/bjc/functypes/Container.java b/src/main/java/bjc/functypes/Container.java
new file mode 100644
index 0000000..f000705
--- /dev/null
+++ b/src/main/java/bjc/functypes/Container.java
@@ -0,0 +1,22 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package bjc.functypes;
+
+public interface Container<T, C extends Container<?, C>> {
+	// Marker
+}
diff --git a/src/main/java/bjc/functypes/ElseFunction.java b/src/main/java/bjc/functypes/ElseFunction.java
index b37fba8..930e167 100644
--- a/src/main/java/bjc/functypes/ElseFunction.java
+++ b/src/main/java/bjc/functypes/ElseFunction.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 import java.util.Optional;
diff --git a/src/main/java/bjc/functypes/Fixpoints.java b/src/main/java/bjc/functypes/Fixpoints.java
index 6d5a250..132d06c 100644
--- a/src/main/java/bjc/functypes/Fixpoints.java
+++ b/src/main/java/bjc/functypes/Fixpoints.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 import java.util.*;
diff --git a/src/main/java/bjc/functypes/ForEach.java b/src/main/java/bjc/functypes/ForEach.java
index 5c39298..964163f 100644
--- a/src/main/java/bjc/functypes/ForEach.java
+++ b/src/main/java/bjc/functypes/ForEach.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 import java.util.LinkedHashMap;
diff --git a/src/main/java/bjc/functypes/FunctionalIsomorphism.java b/src/main/java/bjc/functypes/FunctionalIsomorphism.java
index 8518338..43520e3 100644
--- a/src/main/java/bjc/functypes/FunctionalIsomorphism.java
+++ b/src/main/java/bjc/functypes/FunctionalIsomorphism.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 import java.util.function.Function;
diff --git a/src/main/java/bjc/functypes/ID.java b/src/main/java/bjc/functypes/ID.java
index 53a4c84..b9ef240 100644
--- a/src/main/java/bjc/functypes/ID.java
+++ b/src/main/java/bjc/functypes/ID.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 import java.util.function.UnaryOperator;
diff --git a/src/main/java/bjc/functypes/IntArrayChooser.java b/src/main/java/bjc/functypes/IntArrayChooser.java
index 416487e..1a62f41 100644
--- a/src/main/java/bjc/functypes/IntArrayChooser.java
+++ b/src/main/java/bjc/functypes/IntArrayChooser.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 /**
diff --git a/src/main/java/bjc/functypes/Isomorphism.java b/src/main/java/bjc/functypes/Isomorphism.java
index db633e6..3393ed6 100644
--- a/src/main/java/bjc/functypes/Isomorphism.java
+++ b/src/main/java/bjc/functypes/Isomorphism.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 import java.util.function.*;
diff --git a/src/main/java/bjc/functypes/ListC.java b/src/main/java/bjc/functypes/ListC.java
new file mode 100644
index 0000000..78fbb7a
--- /dev/null
+++ b/src/main/java/bjc/functypes/ListC.java
@@ -0,0 +1,32 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package bjc.functypes;
+
+import java.util.List;
+
+public class ListC<T> implements Container<T, ListC<?>> {
+	private List<T> contained;
+	
+	public ListC(List<T> contained) {
+		this.contained = contained;
+	}
+	
+	public List<T> list() {
+		return contained;
+	}
+}
diff --git a/src/main/java/bjc/functypes/ListFlattener.java b/src/main/java/bjc/functypes/ListFlattener.java
index 91abe9d..fd3f22a 100644
--- a/src/main/java/bjc/functypes/ListFlattener.java
+++ b/src/main/java/bjc/functypes/ListFlattener.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 import java.util.function.Function;
diff --git a/src/main/java/bjc/functypes/Natural.java b/src/main/java/bjc/functypes/Natural.java
new file mode 100644
index 0000000..ecf12c4
--- /dev/null
+++ b/src/main/java/bjc/functypes/Natural.java
@@ -0,0 +1,34 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package bjc.functypes;
+
+@FunctionalInterface
+public interface Natural<F extends Container<?, F>, G extends Container<?, G>> extends BiContainer<F, G, Natural<?, ?>> {
+	<X> Container<X, G> apply(Container<X, F> val);
+
+	public static Natural<ListC<?>, ListC<?>> listID() {
+		return new Natural<>() {
+			@Override
+			public <X> ListC<X> apply(Container<X, ListC<?>> val) {
+				ListC<X> lst = (ListC<X>) val;
+				
+				return lst;
+			}
+		};
+	}
+}
diff --git a/src/main/java/bjc/functypes/ThrowFunction.java b/src/main/java/bjc/functypes/ThrowFunction.java
index 3714cad..2ec5bea 100644
--- a/src/main/java/bjc/functypes/ThrowFunction.java
+++ b/src/main/java/bjc/functypes/ThrowFunction.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 import java.util.*;
diff --git a/src/main/java/bjc/functypes/Thrower.java b/src/main/java/bjc/functypes/Thrower.java
index eb03eaf..b0fb770 100644
--- a/src/main/java/bjc/functypes/Thrower.java
+++ b/src/main/java/bjc/functypes/Thrower.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 import java.util.*;
diff --git a/src/main/java/bjc/functypes/TriFunction.java b/src/main/java/bjc/functypes/TriFunction.java
index e93e32d..988b311 100644
--- a/src/main/java/bjc/functypes/TriFunction.java
+++ b/src/main/java/bjc/functypes/TriFunction.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 import java.util.function.BiFunction;
diff --git a/src/main/java/bjc/functypes/Unit.java b/src/main/java/bjc/functypes/Unit.java
index 75bdf62..9c2bca0 100644
--- a/src/main/java/bjc/functypes/Unit.java
+++ b/src/main/java/bjc/functypes/Unit.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes;
 
 /**
diff --git a/src/main/java/bjc/functypes/optics/Lens.java b/src/main/java/bjc/functypes/optics/Lens.java
index 0a7d4cd..c56a016 100644
--- a/src/main/java/bjc/functypes/optics/Lens.java
+++ b/src/main/java/bjc/functypes/optics/Lens.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes.optics;
 
 /**
diff --git a/src/main/java/bjc/functypes/optics/LensX.java b/src/main/java/bjc/functypes/optics/LensX.java
index d2e9c30..0c78370 100644
--- a/src/main/java/bjc/functypes/optics/LensX.java
+++ b/src/main/java/bjc/functypes/optics/LensX.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes.optics;
 
 import static bjc.functypes.optics.Lenses.immutable;
diff --git a/src/main/java/bjc/functypes/optics/Lenses.java b/src/main/java/bjc/functypes/optics/Lenses.java
index 05a64e7..3c4c688 100644
--- a/src/main/java/bjc/functypes/optics/Lenses.java
+++ b/src/main/java/bjc/functypes/optics/Lenses.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes.optics;
 
 import java.util.function.BiConsumer;
diff --git a/src/main/java/bjc/functypes/optics/MutableLens.java b/src/main/java/bjc/functypes/optics/MutableLens.java
index b6fca5d..9c2e635 100644
--- a/src/main/java/bjc/functypes/optics/MutableLens.java
+++ b/src/main/java/bjc/functypes/optics/MutableLens.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes.optics;
 
 /**
diff --git a/src/main/java/bjc/functypes/optics/Optic.java b/src/main/java/bjc/functypes/optics/Optic.java
index 949eeca..513e110 100644
--- a/src/main/java/bjc/functypes/optics/Optic.java
+++ b/src/main/java/bjc/functypes/optics/Optic.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes.optics;
 
 /**
diff --git a/src/main/java/bjc/functypes/optics/PrismX.java b/src/main/java/bjc/functypes/optics/PrismX.java
index a9c0dd2..b62bce3 100644
--- a/src/main/java/bjc/functypes/optics/PrismX.java
+++ b/src/main/java/bjc/functypes/optics/PrismX.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes.optics;
 
 public interface PrismX<W1, W2, P1, P2> extends Optic<W1, W2, P1, P2> {
diff --git a/src/main/java/bjc/functypes/optics/impl/package-info.java b/src/main/java/bjc/functypes/optics/impl/package-info.java
index f309401..8ca00cf 100644
--- a/src/main/java/bjc/functypes/optics/impl/package-info.java
+++ b/src/main/java/bjc/functypes/optics/impl/package-info.java
@@ -1 +1,18 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package bjc.functypes.optics.impl;
\ No newline at end of file
diff --git a/src/main/java/bjc/functypes/optics/package-info.java b/src/main/java/bjc/functypes/optics/package-info.java
index c187df9..a3f656c 100644
--- a/src/main/java/bjc/functypes/optics/package-info.java
+++ b/src/main/java/bjc/functypes/optics/package-info.java
@@ -1,3 +1,20 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 /**
  * 
  */