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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 request(self, subject, callback, msg=None):
 """ ublish a message with an implicit inbox listener as the reply. Message is optional. Args: subject (string):
 a string with the subject callback (function):
 callback to be called msg (string=None):
 payload string """

        inbox = self._build_inbox()
        s = self.subscribe(inbox, callback)
        self.unsubscribe(s, 1)
        self.publish(subject, msg, inbox)

        return s