Modify quantity and/or limit price of an active order for the instrument

        :Parameters:
            orderId : int
                the order id to modify

        :Optional:
            quantity : int
                the required quantity of the modified order
            limit_price : int
                the new limit price of the modified order

def modify_order(self, orderId, quantity=None, limit_price=None):
        """Modify quantity and/or limit price of an active order for the instrument

        :Parameters:
            orderId : int
                the order id to modify

        :Optional:
            quantity : int
                the required quantity of the modified order
            limit_price : int
                the new limit price of the modified order
        """
        return self.parent.modify_order(self, orderId, quantity, limit_price)