def difference_update(self, other):
        set.difference_update(self, other)
        self._list = [a for a in self._list if self in a]
        return self
dataset/ETHPy150Open RoseOu/flasky/venv/lib/python2.7/site-packages/sqlalchemy/util/_collections.py/OrderedSet.difference_update/swapped operands of `in`