Diese Funktionen können mit `async def` oder normalem `def` deklariert werden.

### `startup`-Event { #startup-event }

Um eine Funktion hinzuzufügen, die vor dem Start der Anwendung ausgeführt werden soll, deklarieren Sie diese mit dem Event `startup`:

{* ../../docs_src/events/tutorial001_py39.py hl[8] *}

In this case, the `startup` event handler function will initialize the items "database" (just a `dict`) with some values.

You can add more than one event handler function.

And your application won't start receiving requests until all the `startup` event handlers have completed.

### `shutdown` event { #shutdown-event }

To add a function that should be run when the application is shutting down, declare it with the event `"shutdown"`:

![Events Diagram](../assets/images/events@2x.png)

Here’s a [sample event listener](https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/PrintEventsNonConcurrent.java) that prints each event with a timestamp.

```java

首先要注意的是，我们定义了一个带有 `yield` 的异步函数。这与带有 `yield` 的依赖项非常相似。

```Python hl_lines="14-19"
{!../../docs_src/events/tutorial003.py!}
```

这个函数在 `yield`之前的部分，会在应用启动前执行。

剩下的部分在 `yield` 之后，会在应用完成后执行。

## 异步上下文管理器

如你所见，这个函数有一个装饰器 `@asynccontextmanager` 。

它将函数转化为所谓的“**异步上下文管理器**”。

```Python hl_lines="1  13"
{!../../docs_src/events/tutorial003.py!}
```

在 Python 中，  **上下文管理器**是一个你可以在 `with` 语句中使用的东西，例如，`open()` 可以作为上下文管理器使用。

Essas funções podem ser declaradas com `async def` ou `def` normal.

### Evento `startup` { #startup-event }

Para adicionar uma função que deve rodar antes de a aplicação iniciar, declare-a com o evento `"startup"`:

{* ../../docs_src/events/tutorial001_py39.py hl[8] *}

Nesse caso, a função de manipulador do evento `startup` inicializará os itens do "banco de dados" (apenas um `dict`) com alguns valores.

Estas funciones pueden ser declaradas con `async def` o `def` normal.

### Evento `startup` { #startup-event }

Para añadir una función que debería ejecutarse antes de que la aplicación inicie, declárala con el evento `"startup"`:

{* ../../docs_src/events/tutorial001_py39.py hl[8] *}

En este caso, la función manejadora del evento `startup` inicializará los ítems de la "base de datos" (solo un `dict`) con algunos valores.

events@2x.png...

          }
        };

    @Override
    void dispatch(Object event, Iterator<Subscriber> subscribers) {
      checkNotNull(event);
      checkNotNull(subscribers);
      // requireNonNull accommodates Android's @RecentlyNullable annotation on ThreadLocal.get
      Queue<Event> queueForThread = requireNonNull(queue.get());
      queueForThread.offer(new Event(event, subscribers));

      if (!dispatching.get()) {

	}
	globalTransitionState.queueTransitionTask(obj, event, src)
	return true
}

func applyExpiryOnTransitionedObject(ctx context.Context, objLayer ObjectLayer, obj ObjectInfo, lcEvent lifecycle.Event, src lcEventSrc) (ok bool) {
	timeILM := globalScannerMetrics.timeILM(lcEvent.Action)
	if err := expireTransitionedObject(ctx, objLayer, &obj, lcEvent, src); err != nil {
		if isErrObjectNotFound(err) || isErrVersionNotFound(err) {

(this._pointerEvent) {\n      $(this._element).on(EVENT_POINTERDOWN, event => start(event))\n      $(this._element).on(EVENT_POINTERUP, event => end(event))\n\n      this._element.classList.add(CLASS_NAME_POINTER_EVENT)\n    } else {\n      $(this._element).on(EVENT_TOUCHSTART, event => start(event))\n      $(this._element).on(EVENT_TOUCHMOVE, event => move(event))\n      $(this._element).on(EVENT_TOUCHEND, event => end(event))\n    }\n  }\n\n  _keydown(event) {\n    if (/input|textarea/i.test(event.target.tagName))...