--- a/entities/adapters.py	Thu Jun 10 16:57:00 2010 +0200
+++ b/entities/adapters.py	Thu Jun 10 16:57:02 2010 +0200
@@ -22,6 +22,7 @@
 __docformat__ = "restructuredtext en"
 
 from itertools import chain
+from warnings import warn
 
 from logilab.mtconverter import TransformError
 from logilab.common.decorators import cached