correct_username_bytes = b"stanleyjobson"
    is_correct_username = secrets.compare_digest(
        current_username_bytes, correct_username_bytes
    )
    current_password_bytes = credentials.password.encode("utf8")
    correct_password_bytes = b"swordfish"
    is_correct_password = secrets.compare_digest(
        current_password_bytes, correct_password_bytes
    )

If you added the return type annotation, tools and editors would complain with a (correct) error telling you that your function is returning a type (e.g. a dict) that is different from what you declared (e.g. a Pydantic model).

```

but this time at the URL with the prefix path provided by the proxy: `/api/v1`.

Of course, the idea here is that everyone would access the app through the proxy, so the version with the path prefix `/api/v1` is the "correct" one.

And the version without the path prefix (`http://127.0.0.1:8000/app`), provided by Uvicorn directly, would be exclusively for the _proxy_ (Traefik) to access it.

You will see the automatic API docs for the sub-application, including only its own _path operations_, all under the correct sub-path prefix `/subapi`:

<img src="/img/tutorial/sub-applications/image02.png">

                    "type": "value_error.str.regex",
                    "ctx": {"pattern": "password"},
                }
            ]
        }
    )


def test_strict_login_correct_data():
    response = client.post(
        "/login",
        data={"username": "johndoe", "password": "secret", "grant_type": "password"},
    )
    assert response.status_code == 200

And open the docs at <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>.

You will see the automatic API docs, including the paths from all the submodules, using the correct paths (and prefixes) and the correct tags:

<img src="/img/tutorial/bigger-applications/image01.png">

## Include the same router multiple times with different `prefix`

<img src="/img/deployment/https/https07.svg">

The client (browser) will know that the response comes from the correct server because it is using the cryptography they agreed using the **HTTPS certificate** before.

### Multiple Applications

Mais ensuite, même si vous n'avez pas encore vos burgers 🍔, votre travail avec le serveur 💁 est "en pause" ⏸, car vous devez attendre 🕙 que vos burgers soient prêts.

A command line tool that will **process your code** and update most of the things **automatically** for you. Make sure you have your code in git first, and review each of the changes to make sure everything is correct before committing the changes.

### Pydantic v1

**This version of FastAPI still supports Pydantic v1**. And although Pydantic v1 will be deprecated at some point, it will still be supported for a while.

    correct_username_bytes = b"stanleyjobson"
    is_correct_username = secrets.compare_digest(
        current_username_bytes, correct_username_bytes
    )
    current_password_bytes = credentials.password.encode("utf8")
    correct_password_bytes = b"swordfish"
    is_correct_password = secrets.compare_digest(
        current_password_bytes, correct_password_bytes
    )