zb0001Len--
		zb0001Mask |= 0x4
	}
	// variable map header, size zb0001Len
	err = en.Append(0x80 | uint8(zb0001Len))
	if err != nil {
		return
	}

	// skip if no fields are to be emitted
	if zb0001Len != 0 {
		// write "ID"
		err = en.Append(0xa2, 0x49, 0x44)
		if err != nil {
			return
		}
		err = en.WriteBytes((z.VersionID)[:])
		if err != nil {

La classe `BackgroundTasks` provient directement de [`starlette.background`](https://www.starlette.dev/background/).

Elle est importée/incluse directement dans **FastAPI** pour que vous puissiez l'importer depuis `fastapi` et éviter d'importer accidentellement `BackgroundTask` (sans `s` à la fin) depuis `starlette.background`.

            if (!future.isDone()) {
              errorMessage.set("Set call exited before future was complete.");
            }
          });
      executor.execute(
          () -> {
            future.setException(new IllegalArgumentException("failure"));
            if (!future.isDone()) {
              errorMessage.set("SetException call exited before future was complete.");
            }
          });

  @Override
  public double doubleValue() {
    return get();
  }

  /**
   * Saves the state to a stream (that is, serializes it).
   *
   * @serialData The current value is emitted (a {@code double}).
   */
  private void writeObject(ObjectOutputStream s) throws IOException {
    s.defaultWriteObject();

    s.writeDouble(get());
  }

FastAPI met en œuvre certaines bonnes pratiques SSE prêtes à l’emploi.

- Envoyer un commentaire **« keep alive » `ping`** toutes les 15 secondes quand aucun message n’a été émis, pour éviter que certains proxys ne ferment la connexion, comme suggéré dans la [Spécification HTML : Server-Sent Events](https://html.spec.whatwg.org/multipage/server-sent-events.html#authoring-notes).

      throws InterruptedException {
    while (!isThreadBlockedOnInstanceOf(t, blocker)) {
      if (t.getState() == Thread.State.TERMINATED) {
        throw new RuntimeException("Thread " + t + " exited unexpectedly");
      }
      Thread.sleep(1);
    }
  }

  private static boolean isThreadBlockedOnInstanceOf(Thread t, Class<?> blocker) {

      throws InterruptedException {
    while (!isThreadBlockedOnInstanceOf(t, blocker)) {
      if (t.getState() == Thread.State.TERMINATED) {
        throw new RuntimeException("Thread " + t + " exited unexpectedly");
      }
      Thread.sleep(1);
    }
  }

  private static boolean isThreadBlockedOnInstanceOf(Thread t, Class<?> blocker) {

      }
      b.append(',').append(' ');
    }
  }

  /**
   * Saves the state to a stream (that is, serializes it).
   *
   * @serialData The length of the array is emitted (int), followed by all of its elements (each a
   *     {@code double}) in the proper order.
   */
  private void writeObject(ObjectOutputStream s) throws IOException {
    s.defaultWriteObject();

        assertTrue(permissionDenied.getMessage().contains("Permission denied"));

        // Scenario 4: Exit code error
        CommandExecutionException exitCodeError = new CommandExecutionException("Command exited with non-zero code: 127");
        assertTrue(exitCodeError.getMessage().contains("non-zero code"));
    }

@keepalive_app.get("/slow-async", response_class=EventSourceResponse)
async def slow_async_stream():
    yield {"n": 1}
    # Sleep longer than the (monkeypatched) ping interval so a keepalive
    # comment is emitted before the next item.
    await asyncio.sleep(0.3)
    yield {"n": 2}


@keepalive_app.get("/slow-sync", response_class=EventSourceResponse)
def slow_sync_stream():
    yield {"n": 1}
    time.sleep(0.3)