diff -r 9712294e60b9 -r 15ce4c1c8313 doc-src/Tutorial/Datatype/lookupempty.ML
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/doc-src/Tutorial/Datatype/lookupempty.ML	Thu Nov 12 16:45:40 1998 +0100
@@ -0,0 +1,3 @@
+Goal "lookup (Trie None []) as = None";
+by(exhaust_tac "as" 1);
+by(Auto_tac);