Esse código não será executado em seu aplicativo, nós só precisamos dele para *documentar* como essa *API externa* deveria ser.

Mas, você já sabe como criar facilmente documentação automática para uma API com o **FastAPI**.

Então vamos usar esse mesmo conhecimento para documentar como a *API externa* deveria ser... criando as *operações de rota* que a *API externa* deveria implementar (as que sua API irá chamar).

/// info

Even after OpenAPI 3.1.0 was released with this new simpler integration with JSON Schema, for a while, Swagger UI, the tool that provides the automatic docs, didn't support OpenAPI 3.1.0 (it does since version 5.0.0 🎉).

Because of that, versions of FastAPI previous to 0.99.0 still used versions of OpenAPI lower than 3.1.0.

///

* Это также позволяет использовать автоматическую **генерацию клиентского кода** на многих языках.

### Автоматическая документация { #automatic-docs }

Интерактивная документация для API и исследовательские веб-интерфейсы. Поскольку фреймворк основан на OpenAPI, существует несколько вариантов документирования, 2 из них включены по умолчанию.

Veja como poderia ser:

{* ../../docs_src/dependencies/tutorial013_an_py310.py *}

O código de saída, o fechamento automático da `Session` em:

{* ../../docs_src/dependencies/tutorial013_an_py310.py ln[19:21] *}

...seria executado depois que a resposta terminar de enviar os dados lentos:

This code won't be executed in your app, we only need it to *document* how that *external API* should look like.

But, you already know how to easily create automatic documentation for an API with **FastAPI**.

 * <strong>SECURITY NOTE:</strong> When accepting file paths from untrusted sources,
 * always validate them using {@link #isPathSafe(Path, Path)} to prevent path traversal attacks.
 * Methods that accept path strings do not perform automatic validation to maintain backward compatibility.
 * </p>
 *
 * @author higa
 */
public abstract class FileUtil {

    /**
     * Do not instantiate.
     */
    protected FileUtil() {
    }

Verás la documentación interactiva automática de la API (proporcionada por <a href="https://github.com/swagger-api/swagger-ui" class="external-link" target="_blank">Swagger UI</a>):

![Swagger UI](https://fastapi.tiangolo.com/img/index/index-01-swagger-ui-simple.png)

Here's how it could look like:

{* ../../docs_src/dependencies/tutorial013_an_py310.py *}

The exit code, the automatic closing of the `Session` in:

{* ../../docs_src/dependencies/tutorial013_an_py310.py ln[19:21] *}

...would be run after the the response finishes sending the slow data:

  @get:JvmName("cacheResponse") val cacheResponse: Response?,
  /**
   * Returns the response for the HTTP redirect or authorization challenge that triggered this
   * response, or null if this response wasn't triggered by an automatic retry. The body of the
   * returned response should not be read because it has already been consumed by the redirecting
   * client.
   */
  @get:JvmName("priorResponse") val priorResponse: Response?,
  /**

/// warning | Advertencia

Una `Response` devuelta directamente por tu *path operation function* no se documentará en OpenAPI (por ejemplo, el `Content-Type` no se documentará) y no será visible en la documentación interactiva automática.

///

/// info | Información

Por supuesto, el `Content-Type` header real, el código de estado, etc., provendrán del objeto `Response` que devolviste.

///