public Node parse() throws ScanException {
        if (tokenList == null || tokenList.isEmpty())
            return null;
        return E();
    }
@Test
    public void withNoClosingBraces() throws ScanException {
        Tokenizer tokenizer = new Tokenizer("a${b");
        Parser parser = new Parser(tokenizer.tokenize());
        try {
            parser.parse();
        } catch (IllegalArgumentException e) {
            assertEquals("All tokens consumed but was expecting \"}\"", e.getMessage());
            return;
        }
        fail();
    }