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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 __response_url(self, message_id):
 """ URL for responding to agent requests. """

        if self.from_.pid != 0:
            path = AGENT_RESPONSE_PATH % (self.from_.pid, message_id)

        return "http://%s:%s/%s" % (self.host, self.port, path)