public function getResultMessage() {
    // We're only handling the results that our code actually generates.
    switch ($this->result_code) {
      case self::RES_SUCCESS:
        return "SUCCESS";
      case self::RES_FAILURE:
        return "FAILURE";
      case self::RES_NOTSTORED:
        return "NOT STORED";
      case self::RES_NOTFOUND:
        return "NOT FOUND";
    }
    return "UNKNOWN";
  }