adapted to new PureThy.add_axioms_i;

--- a/src/Pure/axclass.ML	Wed Apr 29 11:13:22 1998 +0200
+++ b/src/Pure/axclass.ML	Wed Apr 29 11:14:34 1998 +0200
@@ -217,7 +217,8 @@
     val intro_axm = Logic.list_implies
       (map inclass super_classes @ map (int_axm o snd) axioms, inclass class);
   in
-    PureThy.add_store_axioms_i ((raw_class ^ "I", intro_axm) :: abs_axioms) thy
+    thy
+    |> PureThy.add_axioms_i (map Attribute.none ((raw_class ^ "I", intro_axm) :: abs_axioms))
   end;