public void CalculateTreeTest3()
        {
            string expr = "(/ (+ 1 1) 0)";

            tree = CreateTree.TreeBuilder(expr);
            tree.CalculateTree();
        }
        public void CalculateTreeTest2()
        {
            string expr = "(* (+ 1 1) 2)";

            tree = CreateTree.TreeBuilder(expr);
            Assert.AreEqual(4, tree.CalculateTree());
        }