src/Provers/classical.ML

--- a/src/Provers/classical.ML	Wed Oct 20 17:11:46 2021 +0200
+++ b/src/Provers/classical.ML	Wed Oct 20 18:13:17 2021 +0200
@@ -614,7 +614,6 @@
 (
   type T = claset;
   val empty = empty_cs;
-  val extend = I;
   val merge = merge_cs;
 );