public LevenshteinDistance(string a, string b)
        {
            _first  = a;
            _second = b;

            _matrix = new LetterMatrix(_first, _second);
        }
        public DamerauLevenshtein(string a, string b)
        {
            _first  = a;
            _second = b;

            _matrix = new LetterMatrix(_first, _second);
        }
 public LevenshteinRecursive(string a, string b)
 {
     _wordA  = a;
     _wordB  = b;
     _matrix = new LetterMatrix(a, b);
 }