def add_item(self, item):
        # protect against class registration race condition against
        # asynchronous garbage collection calling _remove_item,
        # [ticket:3208]
        modules = set([
            cls.__module__ for cls in
            [ref() for ref in self.contents] if cls is not None])
        if modules in item.__module__:
            util.warn(
                "This declarative base already contains a class with the "
                "same class name and module name as %s.%s, and will "
                "be replaced in the string-lookup table." % (
                    item.__module__,
                    item.__name__
                )
            )
        self.contents.add(weakref.ref(item, self._remove_item))
dataset/ETHPy150Open RoseOu/flasky/venv/lib/python2.7/site-packages/sqlalchemy/ext/declarative/clsregistry.py/_MultipleClassMarker.add_item/swapped operands of `in`