public int GetHashCode(SortedSet <T> obj)
 {
     return(SetEqualityComparer <T> .GetHashCode(obj, _equalityComparer));
 }
 public bool Equals([AllowNull] SortedSet <T> x, [AllowNull] SortedSet <T> y)
 {
     return(SetEqualityComparer <T> .Equals(x, y, _equalityComparer));
 }