public static CustomsListClass <T> operator -(CustomsListClass <T> listOne, CustomsListClass <T> listTwo)
        {
            CustomsListClass <T> result = listOne + new CustomsListClass <T>();

            for (int i = 0; i < listTwo.count; i++)
            {
                result.Remove(listTwo[i]);
            }
            return(result);
        }
        public static CustomsListClass <T> operator+(CustomsListClass <T> listOne, CustomsListClass <T> listTwo)
        {
            CustomsListClass <T> result = new CustomsListClass <T>();

            for (int i = 0; i < listOne.count; i++)
            {
                result.Add(listOne[i]);
            }
            for (int j = 0; j < listTwo.count; j++)
            {
                result.Add(listTwo[j]);
            }
            return(result);
        }
        public CustomsListClass <T> Zip(CustomsListClass <T> listOne, CustomsListClass <T> listTwo)
        {
            CustomsListClass <T> result = new CustomsListClass <T>();

            for (int i = 0; i < listOne.count || i < listTwo.count; i++)
            {
                if (i < listOne.count)
                {
                    result.Add(listOne[i]);
                }
                if (i < listTwo.count)
                {
                    result.Add(listTwo[i]);
                }
            }
            return(result);
        }