static void Main(string[] args)
        {
            Tree tree = new Tree();
            Node node = tree.Create();

            Console.WriteLine("In Order");
            tree.PrintInOrder(node);
            Console.WriteLine();
            Console.WriteLine();

            Console.WriteLine("Post Order");
            tree.PrintPostOrder(node);
            Console.WriteLine();
            Console.WriteLine();

            Console.WriteLine("Pre Order");
            tree.PrintPreOrder(node);
        }