* `expose_headers` - Indicate any response headers that should be made accessible to the browser. Defaults to `[]`.
* `max_age` - Sets a maximum time in seconds for browsers to cache CORS responses. Defaults to `600`.

The middleware responds to two particular types of HTTP request...

# İlk Adımlar

En sade FastAPI dosyası şu şekilde görünür:

```Python
{!../../../docs_src/first_steps/tutorial001.py!}
```

Yukarıdaki içeriği bir `main.py` dosyasına kopyalayalım.

Uygulamayı çalıştıralım:

<div class="termy">

```console
$ uvicorn main:app --reload

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)

Docker has been one of the main tools to create and manage **container images** and **containers**.

And there's a public <a href="https://hub.docker.com/" class="external-link" target="_blank">Docker Hub</a> with pre-made **official container images** for many tools, environments, databases, and applications.

For example, there's an official <a href="https://hub.docker.com/_/python" class="external-link" target="_blank">Python Image</a>.

If you use a `try` block in a dependency with `yield`, you'll receive any exception that was thrown when using the dependency.

For example, if some code at some point in the middle, in another dependency or in a *path operation*, made a database transaction "rollback" or create any other error, you will receive the exception in your dependency.

So, you can look for that specific exception inside the dependency with `except SomeException`.