private static function parseLanguage($code)
    {
        $lang = substr($code, 0, 2);
        foreach (self::codes() as $code) {
            if ($code['code'] == strtolower($lang)) {
                return [strtolower($lang), $code['description']];
            }
        }

        throw new UnknownLanguageCodeException(
            "The language code '{$code}'' is unknown."
        );
    }