public function valid(\DateTime $now)
    {
        if (false === $this->checkMinute($now)) {
            return false;
        }
        if (false === $this->checkHour($now)) {
            return false;
        }
        if (false === $this->checkDay($now)) {
            return false;
        }
        if (false === $this->checkMonth($now)) {
            return false;
        }
        if (false === $this->checkDayOfWeek($now)) {
            return false;
        }

        return true;
    }