def symmetric_difference(self, other):
        other = set(other)
        result = self.__class__(a for a in self if a not in other)
        result.update(a for a in other if a not in self)
        return result
dataset/ETHPy150Open RoseOu/flasky/venv/lib/python2.7/site-packages/sqlalchemy/util/_collections.py/OrderedSet.symmetric_difference/original