--- a/src/HOL/Data_Structures/Tree2.thy Thu Apr 23 22:54:23 2020 +0200
+++ b/src/HOL/Data_Structures/Tree2.thy Thu Apr 23 23:08:29 2020 +0200
@@ -1,3 +1,5 @@
+section \<open>Augmented Tree (Tree2)\<close>
+
theory Tree2
imports "HOL-Library.Tree"
begin