public String transform() throws ScanException {
    StringBuilder stringBuilder = new StringBuilder();
    compileNode(node, stringBuilder, new Stack<Node>());
    return stringBuilder.toString();
  }
@Test
  public void withDefaultValue() throws ScanException {
    String input = "${k67:-b}c";
    Node node = makeNode(input);
    NodeToStringTransformer nodeToStringTransformer = new NodeToStringTransformer(node, propertyContainer0);
    assertEquals("bc", nodeToStringTransformer.transform());
  }