private function hasValidEnEnding($word)
    {
        $lastLetter = Utf8::substr($word, -1, 1);
        if (in_array($lastLetter, self::$vowels)) {
            return false;
        }

        $threeLastLetters = Utf8::substr($word, -3, 3);
        if ($threeLastLetters == 'gem') {
            return false;
        }
        return true;
    }