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theano/misc/ordered_set.py

@@ -44,6 +44,8 @@ if MutableSet is not None:
     import weakref
 
     class Link(object):
+        # This make that we need to use a different pickle protocol
+        # then the default.  Othewise, there is pickling errors
         __slots__ = 'prev', 'next', 'key', '__weakref__'
 
         def __getstate__(self):