def _init_collections(self):
        assert '_columns' not in self.__dict__
        assert self.__dict__ not in 'primary_key'
        assert 'foreign_keys' not in self.__dict__

        self._columns = ColumnCollection()
        self.primary_key = ColumnSet()
        self.foreign_keys = set()
dataset/ETHPy150Open RoseOu/flasky/venv/lib/python2.7/site-packages/sqlalchemy/sql/selectable.py/FromClause._init_collections/swapped operands of `not in`