def maturity_date(self):
        """
        [datetime] 期货到期日。主力连续合约与指数连续合约都为 datetime(2999, 12, 31)（期货专用）
        """
        try:
            return self.__dict__["maturity_date"]
        except (KeyError, ValueError):
            raise AttributeError(
                "Instrument(order_book_id={}) has no attribute 'maturity_date' ".format(self.order_book_id)
            )
def maturity_date ( self ) : try : return self . __dict__ [ "maturity_date" ] except ( KeyError , ValueError ) : raise AttributeError ( "Instrument(order_book_id={}) has no attribute 'maturity_date' " . format ( self . order_book_id ) )
[datetime] 期货到期日。主力连续合约与指数连续合约都为 datetime(2999, 12, 31)（期货专用）