@Override
    public String toString() {
      String format = "?%s";
      if (myName != null) format = "{%s}";
      if (myIdx >= 0) format = "[%s]";
      return String.format(format, myName != null ? myName : (myIdx >= 0 ? String.valueOf(myIdx) : "null"));
    }
@Override
    public String toString()