/// <summary>
        /// Returns the values from the ListItemCollection for the items that aren't
        /// selected.
        /// </summary>
        public static IEnumerable <string> NonSelectedValues(this ListItemCollection value)
        {
            var items = value.NonSelectedItems();

            if (items.Count() == 0)
            {
                return(new Collection <string>());
            }

            return(items.Select(x => x.Value));
        }