'method' => function($string, $separator = '-') {
        $_transliteration = ["/ö|œ/" => "o",
            "/ü/" => "u",
            "/Ä/" => "A",
            "/Ü/" => "U",
            "/Ö/" => "O",
            "/À|Á|Â|Ã|Å|Ǻ|Ā|Ă|Ą|Ǎ/" => "A",
            "/à|á|â|ã|å|ǻ|ā|ă|ą|ǎ|ª/" => "a",
            "/Ç|Ć|Ĉ|Ċ|Č/" => "C",
            "/ç|ć|ĉ|ċ|č/" => "c",
            "/Ð|Ď|Đ/" => "D",
            "/ð|ď|đ/" => "d",
            "/È|É|Ê|Ë|Ē|Ĕ|Ė|Ę|Ě/" => "E",
            "/è|é|ê|ë|ē|ĕ|ė|ę|ě/" => "e",
            "/Ĝ|Ğ|Ġ|Ģ/" => "G",
            "/ĝ|ğ|ġ|ģ/" => "g",
            "/Ĥ|Ħ/" => "H",
            "/ĥ|ħ/" => "h",
            "/Ì|Í|Î|Ï|Ĩ|Ī| Ĭ|Ǐ|Į|İ/" => "I",
            "/ì|í|î|ï|ĩ|ī|ĭ|ǐ|į|ı/" => "i",
            "/Ĵ/" => "J",
            "/ĵ/" => "j",
            "/Ķ/" => "K",
            "/ķ/" => "k",
            "/Ĺ|Ļ|Ľ|Ŀ|Ł/" => "L",
            "/ĺ|ļ|ľ|ŀ|ł/" => "I",
            "/Ñ|Ń|Ņ|Ň/" => "N",
            "/ñ|ń|ņ|ň|ʼn/" => "n",
            "/Ò|Ó|Ô|Õ|Ō|Ŏ|Ǒ|Ő|Ơ|Ø|Ǿ/" => "O",
            "/ò|ó|ô|õ|ō|ŏ|ǒ|ő|ơ|ø|ǿ|º/" => "o",
            "/Ŕ|Ŗ|Ř/" => "R",
            "/ŕ|ŗ|ř/" => "r",
            "/Ś|Ŝ|Ş|Ș|Š/" => "S",
            "/ś|ŝ|ş|ș|š|ſ/" => "s",
            "/Ţ|Ț|Ť|Ŧ/" => "T",
            "/ţ|ț|ť|ŧ/" => "t",
            "/Ù|Ú|Û|Ũ|Ū|Ŭ|Ů|Ű|Ų|Ư|Ǔ|Ǖ|Ǘ|Ǚ|Ǜ/" => "U",
            "/ù|ú|û|ũ|ū|ŭ|ů|ű|ų|ư|ǔ|ǖ|ǘ|ǚ|ǜ/" => "u",
            "/Ý|Ÿ|Ŷ/" => "Y",
            "/ý|ÿ|ŷ/" => "y",
            "/Ŵ/" => "W",
            "/ŵ/" => "w",
            "/Ź|Ż|Ž/" => "Z",
            "/ź|ż|ž/" => "z",
            "/Æ|Ǽ/" => "E",
            "/ß/" => "s",
            "/IJ/" => "J",
            "/ij/" => "j",
            "/Œ/" => "E",
            "/ƒ/" => ""];
        $quotedReplacement = preg_quote($separator, '/');
        $merge = [
            '/[^\s\p{Zs}\p{Ll}\p{Lm}\p{Lo}\p{Lt}\p{Lu}\p{Nd}]/mu' => ' ',
            '/[\s\p{Zs}]+/mu' => $separator,
            sprintf('/^[%s]+|[%s]+$/', $quotedReplacement, $quotedReplacement) => '',
        ];
        $map = $_transliteration + $merge;
        unset($_transliteration);
        return preg_replace(array_keys($map), array_values($map), $string);
    },