Alternatively, if you don't have a way to provide a command line option like `--root-path` or equivalent, you can set the `root_path` parameter when creating your FastAPI app:

```Python hl_lines="3"
{!../../../docs_src/behind_a_proxy/tutorial002.py!}
```

Passing the `root_path` to `FastAPI` would be the equivalent of passing the `--root-path` command line option to Uvicorn or Hypercorn.

### About `root_path`

    ```Python hl_lines="31  37"
    {!> ../../../docs_src/response_model/tutorial005.py!}
    ```

!!! tip
    The syntax `{"name", "description"}` creates a `set` with those two values.

    It is equivalent to `set(["name", "description"])`.

#### Using `list`s instead of `set`s

If you forget to use a `set` and use a `list` or `tuple` instead, FastAPI will still convert it to a `set` and it will work correctly:

`Optional[Something]` is actually a shortcut for `Union[Something, None]`, they are equivalent.

This also means that in Python 3.10, you can use `Something | None`:

=== "Python 3.10+"

    ```Python hl_lines="1"
    {!> ../../../docs_src/python_types/tutorial009_py310.py!}
    ```

And multiple processes normally **don't share any memory**. This means that each running process has its own things, variables, and memory. And if you are consuming a large amount of memory in your code, **each process** will consume an equivalent amount of memory.

### Server Memory

**FastAPI** provides a convenience tool to structure your application while keeping all the flexibility.

!!! info
    If you come from Flask, this would be the equivalent of Flask's Blueprints.

## An example file structure

Let's say you have a file structure like this:

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   ├── dependencies.py
│   └── routers

Donc :

```Python
q: Union[str, None] = Query(default=None)
```

... rend le paramètre optionnel, et est donc équivalent à :

```Python
q: Union[str, None] = None
```

Mais déclare explicitement `q` comme étant un paramètre de requête.

!!! info

### Eine `list`e mit einem Typ-Parameter deklarieren

Um Typen wie `list`, `dict`, `tuple` mit inneren Typ-Parametern (inneren Typen) zu deklarieren:

* Wenn Sie eine Python-Version kleiner als 3.9 verwenden, importieren Sie das Äquivalent zum entsprechenden Typ vom `typing`-Modul
* Überreichen Sie den/die inneren Typ(en) von eckigen Klammern umschlossen, `[` und `]`, als „Typ-Parameter“

In Python 3.9 wäre das:

```Python
my_list: list[str]
```

* Build your FastAPI image:

<div class="termy">

```console
$ docker build -t myimage .

---> 100%
```

</div>

!!! tip
    Notice the `.` at the end, it's equivalent to `./`, it tells Docker the directory to use to build the container image.

    In this case, it's the same current directory (`.`).

### Start the Docker Container

* Run a container based on your image:

    {!> ../../../docs_src/security/tutorial003.py!}
    ```

#### About `**user_dict`

`UserInDB(**user_dict)` means:

*Pass the keys and values of the `user_dict` directly as key-value arguments, equivalent to:*

```Python
UserInDB(
    username = user_dict["username"],
    email = user_dict["email"],
    full_name = user_dict["full_name"],
    disabled = user_dict["disabled"],

Você verá algo como:

```JSON
{"item_id": 5, "q": "somequery"}
```

### API interativa de documetação