!!! note
    You don't necessarily need to add different scopes in different places.

    We are doing it here to demonstrate how **FastAPI** handles scopes declared at different levels.

=== "Python 3.10+"

    ```Python hl_lines="4  139  170"
    {!> ../../../docs_src/security/tutorial005_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="4  139  170"

## Dependency Injection

Using `BackgroundTasks` also works with the dependency injection system, you can declare a parameter of type `BackgroundTasks` at multiple levels: in a *path operation function*, in a dependency (dependable), in a sub-dependency, etc.

That information will be included in the generated OpenAPI and used by the documentation user interfaces and external tools.

!!! note
    Keep in mind that different tools might have different levels of OpenAPI support.

    Some of them might not show all the extra information declared yet, although in most of the cases, the missing feature is already planned for development.

You can add a `title`:

    * If the token contains `foobar`, the content of the `Authorization` header would be: `Bearer foobar`.

## **FastAPI**'s `OAuth2PasswordBearer`

**FastAPI** provides several tools, at different levels of abstraction, to implement these security features.

In this example we are going to use **OAuth2**, with the **Password** flow, using a **Bearer** token. We do that using the `OAuth2PasswordBearer` class.

!!! info

    * Original PR [#722](https://github.com/tiangolo/fastapi/pull/722) by [@booooh](https://github.com/booooh).
* Refactor logging to use the same logger everywhere, update log strings and levels. PR [#781](https://github.com/tiangolo/fastapi/pull/781).