--- 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