public void TravInTest()
        {
            BinTree<int> tree = new BinTree<int>(new BinNode<int>(10));
            tree.InsertAsLC(tree.Root(), 15);
            tree.InsertAsLC(tree.Root().LChild, 16);
            tree.InsertAsRC(tree.Root().LChild, 17);
            tree.InsertAsRC(tree.Root(), 20);
            tree.InsertAsLC(tree.Root().RChild, 21);

            int sum = 0;
            tree.TravIn(o => sum += o);
            Assert.IsTrue(sum == 99);
        }