public static function normalize($string, $errmode = self::NORMALIZE_ERRMODE_SILENT)
    {
        $origString = $string;

        $string = strtoupper($string);
        if ($string !== $origString && $errmode) {
            throw new \RuntimeException("String '$origString' requires normalization");
        }

        $string = str_replace('-', '', strtr($string, 'IiLlOo', '111100'));
        if ($string !== $origString && $errmode) {
            throw new \RuntimeException("String '$origString' requires normalization");
        }

        return $string;
    }