code: public void format(StringBuffer fmt, Set done, Set todo, int indent) {
      formatName(fmt, indent);
      fmt.append("[");
      if (fields != null) {
        fmt.append("\n");
        for (int i = 0; i < fields.length; i++) {
          if (i > 0)
            fmt.append(",\n");
          fields[i].format(fmt, done, todo, indent + 2);
        }
        fmt.append("\n");
        indent(fmt, indent);
      }
      fmt.append("]");
    }
docs: Format as string (subroutine of toString)