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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 empty_channel(self, topic, channel):
 """Empty all the queued messages for an existing channel."""

        nsq.assert_valid_topic_name(topic)
        nsq.assert_valid_channel_name(channel)
        return self._request('POST', '/channel/empty',
                             fields={'topic': topic, 'channel': channel})