```Python
with open("file.txt") as file:
    file.read()
```

En versiones recientes de Python, también hay un **async context manager**. Lo usarías con `async with`:

```Python
async with lifespan(app):
    await do_stuff()
```

   * numElements} elements are not available, it will wait for them up to the specified timeout.
   *
   * @param q the blocking queue to be drained
   * @param buffer where to add the transferred elements
   * @param numElements the number of elements to be waited for
   * @param timeout how long to wait before giving up
   * @return the number of elements transferred

   */
  void awaitRunning();

  /**
   * Waits for the {@link Service} to reach the {@linkplain State#RUNNING running state} for no more
   * than the given time.
   *
   * @param timeout the maximum time to wait
   * @throws TimeoutException if the service has not reached the given state within the deadline
   * @throws IllegalStateException if the service reaches a state from which it is not possible to

        awaitTermination(0);
    }

    /**
     * Waits for the crawling process to terminate for a specified duration.
     * @param millis The maximum time to wait in milliseconds. A value of 0 means wait indefinitely.
     */
    public void awaitTermination(final long millis) {
        if (parentThread != null) {
            try {
                parentThread.join(millis);

				atomic.AddUint64(&totalBytesWritten, uint64(info.Size))
				objCountPerThread[i]++
				mu.Lock()
				uploadTimes = append(uploadTimes, response)
				mu.Unlock()
			}
		}(i)
	}
	wg.Wait()

	// We already saw write failures, no need to proceed into read's
	if retError != "" {
		return SpeedTestResult{
			Uploads:     totalBytesWritten,
			Downloads:   totalBytesRead,
			UploadTimes: uploadTimes,

version: 2
updates:
# TODO(b/170636568): Enable Maven updates? Perhaps wait until we can more
# easily import the generated PRs into our internal repo.
#  - package-ecosystem: "maven"
#    directory: "/"
#    schedule:
#      interval: "weekly"
#    groups:
#      dependencies:
#        applies-to: version-updates
#        patterns:
#          - "*"
#  - package-ecosystem: "maven"
#    directory: "/android"
#    schedule:

   * than the given time. The manager will become healthy after all the component services have
   * reached the {@linkplain State#RUNNING running} state.
   *
   * @param timeout the maximum time to wait
   * @throws TimeoutException if not all of the services have finished starting within the deadline
   * @throws IllegalStateException if the service manager reaches a state from which it cannot

				return err
			}
		}

		header, err := tarReader.Next()
		switch {
		// if no more files are found return
		case err == io.EOF:
			wg.Wait()
			return asyncErr

		// return any other error
		case err != nil:
			wg.Wait()
			extra := ""
			if n > 0 {
				extra = fmt.Sprintf(" after %d successful object(s)", n)
			}
			return fmt.Errorf("tar file error: %w%s", err, extra)

with open("file.txt") as file:
    file.read()
```

Nas versões mais recentes de Python, há também um **gerenciador de contexto assíncrono**. Você o usaria com `async with`:

```Python
async with lifespan(app):
    await do_stuff()
```

`from starlette.websockets import WebSocket`을 사용할 수도 있습니다.

**FastAPI**는 개발자를 위한 편의를 위해 동일한 `WebSocket`을 직접 제공합니다. 하지만 이는 Starlette에서 가져옵니다.

///

## 메시지를 대기하고 전송하기

WebSocket 경로에서 메시지를 대기(`await`)하고 전송할 수 있습니다.

{* ../../docs_src/websockets/tutorial001.py hl[48:52] *}

여러분은 이진 데이터, 텍스트, JSON 데이터를 받을 수 있고 전송할 수 있습니다.

## 시도해보기

파일 이름이 `main.py`라고 가정하고 응용 프로그램을 실행합니다:

<div class="termy">