public static function months($format = null) {
        $months = array();

        if ($format === static::MONTHS_LONG || $format === static::MONTHS_SHORT) {
            for ($i = 1; $i <= 12; ++$i) {
                $months[$i] = strftime($format, mktime(0, 0, 0, $i, 1));
            }
        } else {
            $months = static::hours();
        }

        return $months;
    }