public int GetHashCode(RankedSet <T> set)
            {
                int hashCode = 0;

                if (set != null)
                {
                    foreach (T item in set)
                    {
                        hashCode ^= (equalityComparer.GetHashCode(item) & 0x7FFFFFFF);
                    }
                }

                return(hashCode);
            }
 public bool Equals(RankedSet <T> s1, RankedSet <T> s2)
 => RankedSet <T> .RankedSetEquals(s1, s2, comparer);