```Python hl_lines="18-20"
    {!> ../../../docs_src/body_multiple_params/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="18-20"
    {!> ../../../docs_src/body_multiple_params/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="19-21"
    {!> ../../../docs_src/body_multiple_params/tutorial001_an.py!}
    ```

=== "Python 3.10+ non-Annotated"

            gt=gt,
            ge=ge,
            lt=lt,
            le=le,
            min_length=min_length,
            max_length=max_length,
            discriminator=discriminator,
            multiple_of=multiple_of,
            allow_nan=allow_inf_nan,
            max_digits=max_digits,
            decimal_places=decimal_places,
            **extra,
        )
        if examples is not None:

    each OAuth2 flow.

    You normally would not create a new class inheriting from it but use one of the
    existing subclasses, and maybe compose them if you want to support multiple flows.

    Read more about it in the
    [FastAPI docs for Security](https://fastapi.tiangolo.com/tutorial/security/).
    """

    def __init__(
        self,
        *,
        flows: Annotated[

                This is useful when you want to have optional authentication.

                It is also useful when you want to have authentication that can be
                provided in one of multiple optional ways (for example, in HTTP Basic
                authentication or in an HTTP Bearer token).
                """
            ),
        ] = True,
    ):

But in many cases, you will want to run several worker processes at the same time.

### Multiple Processes - Workers

The client (browser) will know that the response comes from the correct server because it is using the cryptography they agreed using the **HTTPS certificate** before.

### Multiple Applications

In the same server (or servers), there could be **multiple applications**, for example, other API programs or a database.

The same would happen if you had something like a <abbr title='A union between multiple types means "any of these types".'>union</abbr> between different types where one or more of them are not valid Pydantic types, for example this would fail 💥:

=== "Python 3.10+"

    ```Python hl_lines="8"

    github_event = PartialGitHubEvent.parse_raw(contents)

    # Avoid race conditions with multiple labels
    sleep_time = random.random() * 10  # random number between 0 and 10 seconds
    logging.info(
        f"Sleeping for {sleep_time} seconds to avoid "
        "race conditions and multiple comments"
    )
    time.sleep(sleep_time)

    # Get PR

<img src="/img/tutorial/bigger-applications/image01.png">

## Include the same router multiple times with different `prefix`

You can also use `.include_router()` multiple times with the *same* router using different prefixes.

This could be useful, for example, to expose the same API under different prefixes, e.g. `/api/v1` and `/api/latest`.

    * Django REST Framework
    * Starlette (in which **FastAPI** is based)
    * Uvicorn (used by Starlette and **FastAPI**)

!!! check "Inspired **FastAPI** to"
    Exist.

    The idea of declaring multiple things (data validation, serialization and documentation) with the same Python types, that at the same time provided great editor support, was something I considered a brilliant idea.