private static string ToString(SortedSetElement element, bool withScores)
        {
            if (element == null)
            {
                return(null);
            }

            if (withScores)
            {
                return($"{element.Member} {element.Score}");
            }

            return(element.Member);
        }
        public void Add(double score, string member)
        {
            var element = new SortedSetElement(score, member);

            Elements.Add(element);
        }