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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 _subscribe(self):
 """ Subscribe to the device. A subscription serves two purposes: - Returns state (on/off). - Enables state changes on the device for a short period of time. """

        cmd = MAGIC + SUBSCRIBE + self._mac \
            + PADDING_1 + self._mac_reversed + PADDING_1
        status = self._udp_transact(cmd, self._subscribe_resp)
        if status is not None:
            self.last_subscribed = time.time()
            return status == ON
        else:
            raise S20Exception(
                "No status could be found for {}".format(self.host))