public function once(bool $set = null)
    {
        if ($set) {
            return $this->setFrequency(AlarmInterface::ONCE);
        }
        return $this->getFrequency() === AlarmInterface::ONCE;
    }
public function once(bool $set = null)
    {
        if ($set) {
            return $this->setFrequency(AlarmInterface::ONCE);
        }
        return $this->getFrequency() === AlarmInterface::ONCE;
    }
public function once ( bool $ set = null ) { if ( $ set ) { return $ this -> setFrequency ( AlarmInterface :: ONCE ) ; } return $ this -> getFrequency ( ) === AlarmInterface :: ONCE ; }
Check or set whether this alarm is a one time only alarm.

@param bool $set Set this alarm to be a one time only alarm

@return bool|AlarmInterface Returns true/false when checking, or AlarmInterface when setting
Check or set whether this alarm is a one time only alarm .