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

And if you declared a `response_model`, it will still be used to filter and convert the object you returned.

**FastAPI** will use that *temporal* response to extract the cookies (also headers and status code), and will put them in the final response that contains the value you returned, filtered by any `response_model`.

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

## Check it

Now, every request under the path `/v1/` will be handled by the Flask application.

And the rest will be handled by **FastAPI**.

If you run it and go to <a href="http://localhost:8000/v1/" class="external-link" target="_blank">http://localhost:8000/v1/</a> you will see the response from Flask:

```txt
Hello, World from Flask!
```

    Also, before that, in previous versions, the `request` object was passed as part of the key-value pairs in the context for Jinja2.

!!! tip
    By declaring `response_class=HTMLResponse` the docs UI will be able to know that the response will be HTML.

!!! note "Technical Details"
    You could also use `from starlette.templating import Jinja2Templates`.

You don't want the original dependency to run (nor any of the sub-dependencies it might have).

Instead, you want to provide a different dependency that will be used only during tests (possibly only some specific tests), and will provide a value that can be used where the value of the original dependency was used.

### Use cases: external service

I will show you some of the main concepts you should probably keep in mind when deploying a **FastAPI** application (although most of it applies to any other type of web application).

    The *path operation* for `swagger_ui_redirect` is a helper for when you use OAuth2.

    If you integrate your API with an OAuth2 provider, you will be able to authenticate and come back to the API docs with the acquired credentials. And interact with it using the real OAuth2 authentication.

    Swagger UI will handle it behind the scenes for you, but it needs this "redirect" helper.

### Create a *path operation* to test it

Python will complain if you put a value with a "default" before a value that doesn't have a "default".

But you can re-order them, and have the value without a default (the query parameter `q`) first.

Most of the standard headers are separated by a "hyphen" character, also known as the "minus symbol" (`-`).

But a variable like `user-agent` is invalid in Python.

So, by default, `Header` will convert the parameter names characters from underscore (`_`) to hyphen (`-`) to extract and document the headers.

          token: ${{ secrets.FASTAPI_ISSUE_MANAGER }}
          config: >
            {
              "answered": {
                "delay": 864000,
                "message": "Assuming the original need was handled, this will be automatically closed now. But feel free to add more comments or create new issues or PRs."
              },
              "changes-requested": {
                "delay": 2628000,

            "title": "ChimichangApp",
            "summary": "Deadpool's favorite app. Nuff said.",
            "description": "\nChimichangApp API helps you do awesome stuff. 🚀\n\n## Items\n\nYou can **read items**.\n\n## Users\n\nYou will be able to:\n\n* **Create users** (_not implemented_).\n* **Read users** (_not implemented_).\n",
            "termsOfService": "http://example.com/terms/",
            "contact": {
                "name": "Deadpoolio the Amazing",