public bool IsEqual(Hashset setValue)
        {
            if (GetCardinality() == setValue.GetCardinality() && IsSubset(setValue))
            {
                return(true);
            }

            return(false);
        }
        public bool IsProperSubset(Hashset setValue)
        {
            if (GetCardinality() > setValue.GetCardinality() && IsSubset(setValue))
            {
                return(true);
            }

            return(false);
        }