It also includes what has changed, how validations are now more correct and strict, possible caveats, etc.

You can read it to understand better what has changed.

## Tests { #tests }

Make sure you have [tests](../tutorial/testing.md){.internal-link target=_blank} for your app and you run them on continuous integration (CI).

0.082 responseBodyStart
0.082 responseBodyEnd
0.083 connectionReleased
0.083 callEnd
```

Notice how no connect events are fired for the second call. It reused the connection from the first request for dramatically better performance.

### EventListener.Factory

{* ../../docs_src/path_params_numeric_validations/tutorial004_an_py39.py hl[10] *}

## Валидация числовых данных: больше и меньше или равно { #number-validations-greater-than-and-less-than-or-equal }

То же самое применимо к:

* `gt`: больше (`g`reater `t`han)
* `le`: меньше или равно (`l`ess than or `e`qual)

## Future { #future }

By this point, it's already clear that **FastAPI** with its ideas is being useful for many people.

It is being chosen over previous alternatives for suiting many use cases better.

Many developers and teams already depend on **FastAPI** for their projects (including me and my team).

But still, there are many improvements and features to come.

**FastAPI** has a great future ahead.

    // GWT's ConcurrentHashMap is a wrapper around HashMap, but it rejects null keys, which matches
    // the behaviour of the non-GWT implementation of newConcurrentHashSet().
    // On the other hand HashSet might be better for code size if apps aren't
    // already using Collections.newSetFromMap and ConcurrentHashMap.
    return Collections.newSetFromMap(new ConcurrentHashMap<E, Boolean>());
  }

   * interned, thus preventing these instances from being garbage-collected. If this retention is
   * acceptable, this implementation may perform better than {@link #newWeakInterner}.
   */
  public static <E> Interner<E> newStrongInterner() {
    return newBuilder().strong().build();
  }

  /**

			// with dead end because tcp-keepalive is not fired when there is data in the socket buffer.
			//    https://blog.cloudflare.com/when-tcp-sockets-refuse-to-die/
			// This is a sensitive configuration, it is better to set it to high values, > 60 secs since it can
			// affect clients reading data with a very slow pace  (disappropriate with socket buffer sizes)
			if opts.UserTimeout > 0 {

 *  Fix: Handle null fragments.
 *  Fix: Don’t crash on interceptors that throw `IOException` before a
    connection is attempted.
 *  New: Support [WebDAV][webdav] HTTP methods.
 *  New: Buffer WebSocket frames for better performance.
 *  New: Drop support for `TLS_DHE_DSS_WITH_AES_128_CBC_SHA`, our only remaining
    DSS cipher suite. This is consistent with Firefox and Chrome which have also
    dropped these cipher suite.

And we know that editors can't provide a lot of support (like completion) for `dict`s, because they can't know their keys and value types.

We can do better...

## What makes a dependency { #what-makes-a-dependency }

Up to now you have seen dependencies declared as functions.

Mas, neste caso, a mesma aplicação **FastAPI** irá lidar com a API e com a autenticação.

Então, vamos rever de um ponto de vista simplificado:

* O usuário digita o `username` e o `password` no frontend e pressiona `Enter`.
* O frontend (rodando no navegador do usuário) envia esse `username` e `password` para uma URL específica na nossa API (declarada com `tokenUrl="token"`).