//------------------------------------------------------------------------------------------------
        public static Frame<string, string> sortFrameByNaturalOrder(Frame<string, string> input, List<string>contractSortOrder )
        //------------------------------------------------------------------------------------------------
        {
            var series = input.GetColumn<string>("ticker").SelectValues(s => futuresSortValue(s, contractSortOrder));

            input.AddColumn("SortValue",series);

            input = input.SortRows("SortValue");

            return input;
        }