code: public void dump(String prefix) {
          System.out.println(toString(prefix));
          if (children != null) {
              for (int i = 0; i < children.length; ++i) {
                  SimpleNode n = (SimpleNode) children[i];
                  if (n != null) {
                      n.dump(prefix + " ");
                  }
              }
          }
      }
docs: /*
  Override this method if you want to customize how the node dumps out its
  children.