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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 ip_messaging(self):
 """ Access the IpMessaging Twilio Domain :returns: IpMessaging Twilio Domain :rtype: twilio.rest.ip_messaging.IpMessaging """

        if self._ip_messaging is None:
            from twilio.rest.ip_messaging import IpMessaging
            self._ip_messaging = IpMessaging(self)
        return self._ip_messaging