send update command(s)

def update(self, space_no, key_tuple, op_list):
        """
        send update command(s)
        """
        d = self.replyQueue.get()
        packet = RequestUpdate(self.charset, self.errors, d._ipro_request_id, space_no, 0, key_tuple, op_list)
        self.transport.write(bytes(packet))
        return d.addCallback(self.handle_reply, self.charset, self.errors, None)