You pay. 💸

The cashier gives you the number of your turn.

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

While you are waiting, you go with your crush and pick a table, you sit and talk with your crush for a long time (as your burgers are very fancy and take some time to prepare).

## Use a `Response` parameter

You can declare a parameter of type `Response` in your *path operation function* (as you can do for cookies).

And then you can set headers in that *temporal* response object.

```Python hl_lines="1  7-8"
{!../../../docs_src/response_headers/tutorial002.py!}
```

And then you can return any object you need, as you normally would (a `dict`, a database model, etc).

For example, let's say that you want to use <a href="https://github.com/ijl/orjson" class="external-link" target="_blank">`orjson`</a>, but with some custom settings not used in the included `ORJSONResponse` class.

Let's say you want it to return indented and formatted JSON, so you want to use the orjson option `orjson.OPT_INDENT_2`.

And the next sections assume you already read it, and assume that you know those main ideas.

## 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.

If you don't select any scope, you will be "authenticated", but when you try to access `/users/me/` or `/users/me/items/` you will get an error saying that you don't have enough permissions. You will still be able to access `/status/`.

And if you select the scope `me` but not the scope `items`, you will be able to access `/users/me/` but not `/users/me/items/`.

Here is the reference for it and its parameters.

You can import it directly from `fastapi`:

```python
from fastapi import Depends
```

::: fastapi.Depends

## `Security()`

For many scenarios, you can handle security (authorization, authentication, etc.) with dependencies, using `Depends()`.

But when you want to also declare OAuth2 scopes, you can use `Security()` instead of `Depends()`.

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

!!! tip
    By the spec, you should return a JSON with an `access_token` and a `token_type`, the same as in this example.

    This is something that you have to do yourself in your code, and make sure you use those JSON keys.

    It's almost the only thing that you have to remember to do correctly yourself, to be compliant with the specifications.

If you are starting a project from scratch, you are probably better off with SQLAlchemy ORM ([SQL (Relational) Databases](../tutorial/sql-databases.md){.internal-link target=_blank}), or any other async ORM.

If you already have a code base that uses <a href="https://docs.peewee-orm.com/en/latest/" class="external-link" target="_blank">Peewee ORM</a>, you can check here how to use it with **FastAPI**.

# Async Tests

You have already seen how to test your **FastAPI** applications using the provided `TestClient`. Up to now, you have only seen how to write synchronous tests, without using `async` functions.

![ReDoc](https://fastapi.tiangolo.com/img/index/index-06-redoc-02.png)

### Recap

In summary, you declare **once** the types of parameters, body, etc. as function parameters.

You do that with standard modern Python types.

You don't have to learn a new syntax, the methods or classes of a specific library, etc.

Just standard **Python 3.8+**.

For example, for an `int`: