public function compareDuration(Period $period)
	    {
	        $datetime = new DateTime();
	        $alt  = clone $datetime;
	        $datetime->add($this->start->diff($this->end));
	        $alt->add($period->start->diff($period->end));
	        
	        if ($datetime > $alt) {
	            return 1;
	        } elseif ($datetime < $alt) {
	            return -1;
	        }

	        return 0;
	    }