public void Test1()
        {
            var num1 = new Node(6)
            {
                Next = new Node(3)
                {
                    Next = new Node(5)
                    {
                        Next = new Node(1)
                    }
                }
            };
            var num2 = new Node(5)
            {
                Next = new Node(6)
            };

            var sum       = _linkedListService.AddTwoNumbers(num1, num2);
            var sumString = _linkedListService.GetLinkedListString(sum);

            Assert.True(sumString == "1061");
        }