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`.

```Python hl_lines="6"
{!../../../docs_src/behind_a_proxy/tutorial001.py!}
```

    ```

=== "Python 3.8+"

    ```Python hl_lines="9  11  16"
    {!> ../../../docs_src/response_model/tutorial003.py!}
    ```

Here, even though our *path operation function* is returning the same input user that contains the password:

=== "Python 3.10+"

    ```Python hl_lines="24"
    {!> ../../../docs_src/response_model/tutorial003_py310.py!}
    ```

* **After** obtaining a secure connection, the communication protocol is **still HTTP**.
    * The contents are **encrypted**, even though they are being sent with the **HTTP protocol**.

    The `Union` in `Union[str, None]` will allow your editor to give you better support and detect errors.

## Additional validation

We are going to enforce that even though `q` is optional, whenever it is provided, **its length doesn't exceed 50 characters**.

### Import `Query` and `Annotated`

To achieve that, first import:

* `Query` from `fastapi`

<img src="/img/async/concurrent-burgers/concurrent-burgers-02.png" class="illustration">

The cashier says something to the cook in the kitchen so they know they have to prepare your burgers (even though they are currently preparing the ones for the previous clients).

<img src="/img/async/concurrent-burgers/concurrent-burgers-03.png" class="illustration">

You pay. 💸

The cashier gives you the number of your turn.