private bool CurrentCharacterMatchesPhoneme(Phoneme phoneme, bool allowVowels = true)
        {
            if (allowVowels && phoneme.Letters.Length == 0 && phoneme.HasVowel() && CurrentCharacter.HasVowel())
            {
                return(true);
            }

            return(phoneme.GetPossibleLetters().Any(each => each == CurrentCharacter));
        }