public String transform() throws ScanException {
        StringBuilder stringBuilder = new StringBuilder();
        compileNode(node, stringBuilder, new Stack<Node>());
        return stringBuilder.toString();
    }
@Test
    public void nestedVariable() throws ScanException {
        String input = "a${k${zero}}b";
        Node node = makeNode(input);
        NodeToStringTransformer nodeToStringTransformer = new NodeToStringTransformer(node, propertyContainer0);
        Assertions.assertEquals("av0b", nodeToStringTransformer.transform());
    }