     public func list(maxResults: Int64) -> Future<StorageListResult, Error> {
       Future<StorageListResult, Error> { promise in
         self.list(maxResults: maxResults) { result in
-          switch result {
-          case let .success(list):
-            promise(.success(list))
-          case let .failure(error):
-            promise(.failure(error))
-          }
+          promise(result)
         }
       }
     }

      var task: StorageDownloadTask?
      return Future<URL, Error> { [weak self] promise in
        task = self?.write(toFile: fileURL) { result in
          switch result {
          case let .success(url):
            promise(.success(url))
          case let .failure(error):
            promise(.failure(error))
          }
        }
      }
      .handleEvents(receiveCancel: {

    public func list(maxResults: Int64, pageToken: String) -> Future<StorageListResult, Error> {
      Future<StorageListResult, Error> { promise in
        self.list(maxResults: maxResults, pageToken: pageToken) { result in
          promise(result)
        }
      }
    }
