Determine if a zone is expired or not.

        :param zone: zone number
        :type zone: int

        :returns: whether or not the zone is expired

def _zone_expired(self, zone):
        """
        Determine if a zone is expired or not.

        :param zone: zone number
        :type zone: int

        :returns: whether or not the zone is expired
        """
        return (time.time() > self._zones[zone].timestamp + Zonetracker.EXPIRE) and self._zones[zone].expander is False