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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 _expired(self):
 """Hold timer expired event handler. """

        LOG.info('Negotiated hold time %s expired.', self._holdtime)
        code = BGP_ERROR_HOLD_TIMER_EXPIRED
        subcode = BGP_ERROR_SUB_HOLD_TIMER_EXPIRED
        self.send_notification(code, subcode)
        self.connection_lost('Negotiated hold time %s expired.' %
                             self._holdtime)
        self.stop()