public static string GetDescription(this FilterOperatorlist filterOperator)
        {
            switch (filterOperator)
            {
            case FilterOperatorlist.Item: return("equals");

            case FilterOperatorlist.isa: return("is, or is a child of");

            case FilterOperatorlist.isnota: return("is not, and is not a child of");

            case FilterOperatorlist.@in: return("is in the set of");

            case FilterOperatorlist.notin: return("is not in the set of");

            case FilterOperatorlist.regex: return("regular expression matches");

            default: throw new NotSupportedException("Filter operator not recognised");
            }
        }
        public static string GetName(this FilterOperatorlist filterOperator)
        {
            switch (filterOperator)
            {
            case FilterOperatorlist.Item: return("=");

            case FilterOperatorlist.isa: return("is-a");

            case FilterOperatorlist.isnota: return("is-not-a");

            case FilterOperatorlist.@in: return("in");

            case FilterOperatorlist.notin: return("not-in");

            case FilterOperatorlist.regex: return("regex");

            default: throw new NotSupportedException("Filter operator not recognised");
            }
        }