Newscoop\Subscription\Issue::getExpirationDate PHP 메소드

    public function getExpirationDate()
    {
        $startDate = isset($this->startDate) ? $this->startDate : new \DateTime('now');
        $timeSpan = new \DateInterval('P' . $this->days . 'D');
        return $startDate->add($timeSpan);
    }