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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:
 def _ack(self, sender, uid, level, payload=None):
 """ Replies to a message """

        content = {'reply-to': uid,
                   'reply-level': level,
                   'payload': payload}
        self.__client.send_message(sender, json.dumps(content))