如何在Flutter中使用枚举作为返回值？

enum RequestStatus {
  success,
  failure,
  loading,
}

RequestStatus makeRequest() {
  // 进行网络请求
  // ...

  if (response.statusCode == 200) {
    return RequestStatus.success;
  } else {
    return RequestStatus.failure;
  }
}

void main() {
  RequestStatus status = makeRequest();

  switch (status) {
    case RequestStatus.success:
      print('请求成功');
      break;
    case RequestStatus.failure:
      print('请求失败');
      break;
    case RequestStatus.loading:
      print('正在加载');
      break;
  }
}