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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 async def ack(self, msg):
 """ Used to manually acks a message. :param msg: Message which is pending to be acked by client. """

        ack_proto = protocol.Ack()
        ack_proto.subject = msg.proto.subject
        ack_proto.sequence = msg.proto.sequence
        await self._nc.publish(msg.sub.ack_inbox, ack_proto.SerializeToString())