public Node parse() throws ScanException {
    if (tokenList == null || tokenList.isEmpty())
      return null;
    return E();
  }
@Test
  public void defaultSeparatorOutsideOfAVariable() throws ScanException {
    Tokenizer tokenizer = new Tokenizer("{a:-b}");
    Parser parser = new Parser(tokenizer.tokenize());
    Node node = parser.parse();

    dump(node);
    Node witness = new Node(Node.Type.LITERAL, "{");
    Node t = witness.next = new Node(Node.Type.LITERAL, "a");


    t.next = new Node(Node.Type.LITERAL, ":-");
    t = t.next;

    t.next = new Node(Node.Type.LITERAL, "b");
    t = t.next;

    t.next = new Node(Node.Type.LITERAL, "}");

    assertEquals(witness, node);
  }