League\Period\Period::compareDuration PHP 메소드

    public function compareDuration(Period $period)
    {
        $datetime = $this->startDate->add($period->getDateInterval());
        if ($this->endDate > $datetime) {
            return 1;
        }
        if ($this->endDate < $datetime) {
            return -1;
        }
        return 0;
    }