And the `--root-path` command line option provides that `root_path`.

### Checking the current `root_path`

You can get the current `root_path` used by your application for each request, it is part of the `scope` dictionary (that's part of the ASGI spec).

Here we are including it in the message just for demonstration purposes.

```Python hl_lines="8"
{!../../../docs_src/behind_a_proxy/tutorial001.py!}
```

This will be the main point of interaction to create all your API.

### Step 3: create a *path operation*

#### Path

"Path" here refers to the last part of the URL starting from the first `/`.

So, in a URL like:

```
https://example.com/items/foo
```

...the path would be:

```
/items/foo
```

!!! info

* Do not change anything enclosed in "``" (inline code).

* In lines starting with `===` or `!!!`, translate only the ` "... Text ..."` part. Leave the rest unchanged.

* You can translate info boxes like `!!! warning` with for example `!!! warning "Achtung"`. But do not change the word immediately after the `!!!`, it determines the color of the info box.

You would probably do this just once, the first time, when setting everything up.

!!! tip
    This Domain Name part is way before HTTPS, but as everything depends on the domain and the IP address, it's worth mentioning it here.

### DNS

Now let's focus on all the actual HTTPS parts.

You want to have the *path operations* related to your users separated from the rest of the code, to keep it organized.

But it's still part of the same **FastAPI** application/web API (it's part of the same "Python Package").

You can create the *path operations* for that module using `APIRouter`.

### Import `APIRouter`

* Kubernetes with an Ingress Controller like Nginx
    * With an external component like cert-manager for certificate renewals
* Handled internally by a cloud provider as part of their services (read below 👇)

* **Coroutines**

## Code asynchrone

Faire du code asynchrone signifie que le langage 💬 est capable de dire à l'ordinateur / au programme 🤖 qu'à un moment du code, il 🤖 devra attendre que *quelque chose d'autre* se termine autre part. Disons que ce *quelque chose d'autre* est appelé "fichier-lent" 📝.

Donc, pendant ce temps, l'ordinateur pourra effectuer d'autres tâches, pendant que "fichier-lent" 📝 se termine.

## Type Hints with Metadata Annotations

Python also has a feature that allows putting **additional metadata** in these type hints using `Annotated`.

=== "Python 3.9+"

    In Python 3.9, `Annotated` is part of the standard library, so you can import it from `typing`.

    ```Python hl_lines="1  4"
    {!> ../../../docs_src/python_types/tutorial013_py39.py!}
    ```

=== "Python 3.8+"

!!! info
    Keep in mind that the most important part to make a parameter optional is the part:

    ```Python
    = None
    ```

    or the:

    ```Python
    = Query(default=None)
    ```

    as it will use that `None` as the default value, and that way make the parameter **not required**.

    But when the form includes files, it is encoded as `multipart/form-data`. If you use `File`, **FastAPI** will know it has to get the files from the correct part of the body.