public static IEnumerable <int> ReadSet(this ITransitionTargets @this, ICharSet set)
 {
     foreach (var cs in @this)
     {
         if (cs.Key.Contains(set))
         {
             return(cs);
         }
     }
     return(Enumerable.Empty <int>());
 }
 public static IEnumerable <int> ReadChar(this ITransitionTargets _this, char key)
 {
     return(_this.Where(g => g.Key != null && g.Key.Includes(key)).SelectMany(g => g).ToArray());
 }