private RhymeGroup NewRhymeGroup()
        {
            var group = new RhymeGroup(RhymeGroups.Count + 1);

            RhymeGroups.Add(group);
            return(group);
        }
 private RhymeGroup FindRhymeGroup(string word)
 {
     return(RhymeGroups.FirstOrDefault(each => each.Words.Contains(word)));
 }