{!> ../../../docs_src/generate_clients/tutorial002_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="23  28  36"
    {!> ../../../docs_src/generate_clients/tutorial002.py!}
    ```

### Generate a TypeScript Client with Tags

If you generate a client for a FastAPI app using tags, it will normally also separate the client code based on the tags.

            It will affect the generated OpenAPI (e.g. visible at `/docs`).
            """
        ),
    ] = None,
    include_in_schema: Annotated[
        bool,
        Doc(
            """
            To include (or not) this parameter field in the generated OpenAPI.
            You probably don't need it, but it's available.

            This affects the generated OpenAPI (e.g. visible at `/docs`).

You can add code to be run with the `request`,  before any *path operation* receives it.

And also after the `response` is generated, before returning it.

For example, you could add a custom header `X-Process-Time` containing the time in seconds that it took to process the request and generate a response:

```Python hl_lines="10  12-13"
{!../../../docs_src/middleware/tutorial001.py!}
```

## Other middlewares

And it generates OpenAPI schemas.

That's how it works in Flask, Starlette, Responder, etc.

But then, we have again the problem of having a micro-syntax, inside of a Python string (a big YAML).

The editor can't help much with that. And if we modify parameters or Marshmallow schemas and forget to also modify that YAML docstring, the generated schema would be obsolete.

!!! info

## Tests

There is a script that you can run locally to test all the code and generate coverage reports in HTML:

<div class="termy">

```console
$ bash scripts/test-cov-html.sh
```

</div>

                It will be included in the generated OpenAPI (e.g. visible at `/docs`).
                """
            ),
        ] = None,
        description: Annotated[
            Optional[str],
            Doc(
                """
                Security scheme description.

                It will be included in the generated OpenAPI (e.g. visible at `/docs`).
                """

                It will be included in the generated OpenAPI (e.g. visible at `/docs`).
                """
            ),
        ] = None,
        description: Annotated[
            Optional[str],
            Doc(
                """
                Security scheme description.

                It will be included in the generated OpenAPI (e.g. visible at `/docs`).
                """

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

### OpenAPI

**FastAPI** generates a "schema" with all your API using the **OpenAPI** standard for defining APIs.

#### "Schema"

A "schema" is a definition or description of something. Not the code that implements it, but just an abstract description.

## Add extra information

You can declare extra information in `Field`, `Query`, `Body`, etc. And it will be included in the generated JSON Schema.

You will learn more about adding extra information later in the docs, when learning to declare examples.

!!! warning

            "description": "Production environment"
        }
    ],
    "paths": {
            // More stuff here
    }
}
```

!!! tip
    Notice the auto-generated server with a `url` value of `/api/v1`, taken from the `root_path`.

In the docs UI at <a href="http://127.0.0.1:9999/api/v1/docs" class="external-link" target="_blank">http://127.0.0.1:9999/api/v1/docs</a> it would look like: