code: private void toStringTree(StringBuilder builder, int indent) {
          for (int count = 0; count < indent; count++) {
              builder.append(" ");
          }
          builder.append(this.toString());
          builder.append("\n");
          if (m_children != null) {
              for (UNode childNode : m_children) {
                  childNode.toStringTree(builder, indent + 3);
              }
          }
      }
docs: appended with a newline.