Process a MQTT presentation message.

def _handle_presentation(self, msg):
        """Process a MQTT presentation message."""
        ret_msg = handle_presentation(msg)
        if msg.child_id == 255 or ret_msg is None:
            return
        # this is a presentation of a child sensor
        topics = [
            '{}/{}/{}/{}/+/+'.format(
                self._in_prefix, str(msg.node_id), str(msg.child_id),
                msg_type)
            for msg_type in (int(self.const.MessageType.set),
                             int(self.const.MessageType.req))
        ]
        topics.append('{}/{}/+/{}/+/+'.format(
            self._in_prefix, str(msg.node_id),
            int(self.const.MessageType.stream)))
        self._handle_subscription(topics)