price: float
    tax: float | None = None

    model_config = {
        "json_schema_extra": {
            "examples": [
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                }
            ]
        }
    }


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):

    price: float
    tax: Union[float, None] = None

    class Config:
        schema_extra = {
            "examples": [
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                }
            ]
        }


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):

* Implement and use well-known cryptographic tools, like Passlib and JWT tokens, etc.
* Add more granular permission controls with OAuth2 scopes where needed.
* ...etc.

Nevertheless, you might have a very specific use case where you really need to disable the API docs for some environment (e.g. for production) or depending on configurations from environment variables.

## Conditional OpenAPI from settings and env vars

This is just a **quick tutorial / refresher** about Python type hints. It covers only the minimum necessary to use them with **FastAPI**... which is actually very little.

**FastAPI** is all based on these type hints, they give it many advantages and benefits.

But even if you never use **FastAPI**, you would benefit from learning a bit about them.

!!! note

    * As we said above, only one process can be listening on a specific IP and port.
    * This is one of the reasons why it's very useful when the same TLS Termination Proxy also takes care of the certificate renewal process.

{!../../../docs_src/bigger_applications/app/main.py!}
```

and it will work correctly, together with all the other *path operations* added with `app.include_router()`.

!!! info "Very Technical Details"
    **Note**: this is a very technical detail that you probably can **just skip**.

    ---

    The `APIRouter`s are not "mounted", they are not isolated from the rest of the application.

## Top Translation Reviewers

These users are the **Top Translation Reviewers**. 🕵️

I only speak a few languages (and not very well 😅). So, the reviewers are the ones that have the [**power to approve translations**](contributing.md#translations){.internal-link target=_blank} of the documentation. Without them, there wouldn't be documentation in several other languages.

We will soon also create the actual path operation.

!!! info
    If you are a very strict "Pythonista" you might dislike the style of the parameter name `tokenUrl` instead of `token_url`.

    * Although it's probably not very problematic here with the way `SQLAlchemy` works.
    * But if you added more code to the middleware that had a lot of <abbr title="input and output">I/O</abbr> waiting, it could then be problematic.
* A middleware is run for *every* request.
    * So, a connection will be created for every request.

To see how to achieve this parallelism in production see the section about [Deployment](deployment/index.md){.internal-link target=_blank}.

## `async` and `await`