public static function systemize($str, $infix = '-')
    {
        $str = self::ascii($str);
        return trim(
            preg_replace(
                '/' . preg_quote($infix, '/') . '+/',
                $infix,
                preg_replace('/[^\w-]+/', $infix, strtolower($str))
            ),
            $infix
        );
    }