This is "synchronous" work, you are "synchronized" with the cashier/cook 👨‍🍳. You have to wait 🕙 and be there at the exact moment that the cashier/cook 👨‍🍳 finishes the burgers and gives them to you, or otherwise, someone else might take them.

<img src="/img/async/parallel-burgers/parallel-burgers-04.png" class="illustration">

Но внутреннее устройство **конкурентности** и **параллелизма** довольно разное.

Чтобы это понять, представьте такую картину:

### Конкурентные бургеры

<!-- The gender neutral cook emoji "🧑‍🍳" does not render well in browsers. In the meantime, I'm using a mix of male "👨‍🍳" and female "👩‍🍳" cooks. -->

{!../../../docs_src/custom_request_and_route/tutorial003.py!}
```

In this example, the *path operations* under the `router` will use the custom `TimedRoute` class, and will have an extra `X-Response-Time` header in the response with the time it took to generate the response:

```Python hl_lines="13-20"
{!../../../docs_src/custom_request_and_route/tutorial003.py!}

{!../../../docs_src/metadata/tutorial001.py!}
```

!!! tip
    You can write Markdown in the `description` field and it will be rendered in the output.

With this configuration, the automatic API docs would look like:

<img src="/img/tutorial/metadata/image01.png">

## License identifier

Since OpenAPI 3.1.0 and FastAPI 0.99.0, you can also set the `license_info` with an `identifier` instead of a `url`.

For example:

      if (connection.isHealthy(doExtensiveHealthChecks)) return connection

      // In the second synchronized block, release the unhealthy acquired connection. We're also on
      // the hook to close this connection if it's no longer in use.
      val noNewExchangesEvent: Boolean
      val toClose: Socket? =
        connection.withLock {
          noNewExchangesEvent = !connection.noNewExchanges

    All the security utilities that integrate with OpenAPI (and the automatic API docs) inherit from `SecurityBase`, that's how **FastAPI** can know how to integrate them in OpenAPI.

## What it does

It will go and look in the request for that `Authorization` header, check if the value is `Bearer ` plus some token, and will return the token as a `str`.

The section:

```Python
from .routers import items, users
```

means:

* Starting in the same package that this module (the file `app/main.py`) lives in (the directory `app/`)...
* look for the subpackage `routers` (the directory at `app/routers/`)...
* and from it, import the submodule `items` (the file at `app/routers/items.py`) and `users` (the file at `app/routers/users.py`)...

- Updated an audit annotation key used by the `…/serviceaccounts/<name>/token`...

* 🔧 Add `CITATION.cff` file for academic citations. PR [#10496](https://github.com/tiangolo/fastapi/pull/10496) by [@tiangolo](https://github.com/tiangolo).
* 🐛 Fix overriding MKDocs theme lang in hook. PR [#10490](https://github.com/tiangolo/fastapi/pull/10490) by [@tiangolo](https://github.com/tiangolo).

## External Courses

Although the [Tutorial - User Guide](../tutorial/index.md){.internal-link target=_blank} and this **Advanced User Guide** are written as a guided tutorial (like a book) and should be enough for you to **learn FastAPI**, you might want to complement it with additional courses.

Or it might be the case that you just prefer to take other courses because they adapt better to your learning style.