public static function dateDiff(DateTime $from = null, DateTime $to = null, string $format = 'Y-m-d H:i:s'): string
    {
        if (!$from) {
            return '';
        }
        if (!$to) { // if not define to then to date is set today
            $to = new DateTime();
        }
        return $from->diff($to)->format($format);
    }