Damit wird auch vermieden, neue Entwickler möglicherweise zu verwirren, die einen nicht verwendeten Parameter in Ihrem Code sehen und ihn für unnötig halten könnten.

!!! info
    In diesem Beispiel verwenden wir zwei erfundene benutzerdefinierte Header `X-Key` und `X-Token`.

Anton Yakovlev <******@****.***> 1712418235 +0300

8. Notice that this *path operation function* uses regular `def` instead of `async def`.

    As always, in FastAPI you can combine `def` and `async def` as needed.

    If you need a refresher about when to use which, check out the section _"In a hurry?"_ in the docs about [`async` and `await`](../async.md#in-a-hurry){.internal-link target=_blank}.

<img src="/img/tutorial/generate-clients/image01.png">

You can see those schemas because they were declared with the models in the app.

That information is available in the app's **OpenAPI schema**, and then shown in the API docs (by Swagger UI).

### `response_model` or Return Type

In this case, because the two models are different, if we annotated the function return type as `UserOut`, the editor and tools would complain that we are returning an invalid type, as those are different classes.

That's why in this example we have to declare it in the `response_model` parameter.

But documentation is still missing. Then APISpec was created.

It is a plug-in for many frameworks (and there's a plug-in for Starlette too).

The way it works is that you write the definition of the schema using YAML format inside the docstring of each function handling a route.

And it generates OpenAPI schemas.

That's how it works in Flask, Starlette, Responder, etc.

!!! tip
    If you want to call `async` functions in your tests apart from sending requests to your FastAPI application (e.g. asynchronous database functions), have a look at the [Async Tests](../advanced/async-tests.md){.internal-link target=_blank} in the advanced tutorial.

## Separating tests

In a real application, you probably would have your tests in a different file.

## Keçən ayın ən fəal istifadəçiləri

Bu istifadəçilər keçən ay [GitHub-da başqalarının suallarına](help-fastapi.md#help-others-with-questions-in-github){.internal-link target=_blank} ən çox kömək edənlərdir. ☕

{% if people %}
<div class="user-list user-list-center">
{% for user in people.last_month_experts[:10] %}

## Geçen Ayın En Aktif Kullanıcıları

Geçtiğimiz ay boyunca [GitHub'da diğerlerine en çok yardımcı olan](help-fastapi.md#help-others-with-questions-in-github){.internal-link target=_blank} kullanıcılar. ☕

{% if people %}
<div class="user-list user-list-center">
{% for user in people.last_month_experts[:10] %}

## Proxy with a stripped path prefix

Having a proxy with a stripped path prefix, in this case, means that you could declare a path at `/app` in your code, but then, you add a layer on top (the proxy) that would put your **FastAPI** application under a path like `/api/v1`.

In this case, the original path `/app` would actually be served at `/api/v1/app`.

Even though all your code is written assuming there's just `/app`.