@Test
    public void simpleNumTest() {
        String input = "(2.0)";
        Lexer lexer = new Lexer(input);
        Parser_v2 Parser_v2 = new Parser_v2(lexer);
        Expression exp = Parser_v2.parse();
        Token num = new Token("2.0");
        Number expected = new Number(num);
        assertEquals(exp.toString(), expected.toString());
    }