clientReader.processNextFrame()
    }.also { expected ->
      assertThat(expected.message)
        .isEqualTo("Control frames must be final.")
    }
  }

  @Test fun reservedFlag1IsUnsupportedWithNoCompression() {
    data.write("ca00".decodeHex()) // Empty pong, flag 1 set.
    assertFailsWith<ProtocolException> {
      clientReader.processNextFrame()
    }.also { expected ->

**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`.

You can also declare the `Response` parameter in dependencies, and set cookies (and headers) in them.

## Return a `Response` directly { #return-a-response-directly }

You can also create cookies when returning a `Response` directly in your code.

Their sponsorship also demonstrates a strong commitment to the FastAPI **community** (you), showing that they care not only about offering a **great service** but also about supporting a **robust and thriving framework**, FastAPI. 🙇

For example, you might want to try:

* Give you the received data in the parameter `item`.
    * As you declared it in the function to be of type `Item`, you will also have all the editor support (completion, etc) for all of the attributes and their types.
* Generate [JSON Schema](https://json-schema.org) definitions for your model, you can also use them anywhere else you like if it makes sense for your project.

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

You can also declare the `Response` parameter in dependencies, and set headers (and cookies) in them.

## Return a `Response` directly { #return-a-response-directly }

You can also add headers when you return a `Response` directly.

And tools will also be happy because both `RedirectResponse` and `JSONResponse` are subclasses of `Response`, so the type annotation is correct.

### Annotate a Response Subclass { #annotate-a-response-subclass }

You can also use a subclass of `Response` in the type annotation:

{* ../../docs_src/response_model/tutorial003_03_py310.py hl[8:9] *}

    * If you also declare dependencies in a specific *path operation*, **they will be executed too**.
    * The router dependencies are executed first, then the [`dependencies` in the decorator](dependencies/dependencies-in-path-operation-decorators.md), and then the normal parameter dependencies.
    * You can also add [`Security` dependencies with `scopes`](../advanced/security/oauth2-scopes.md).

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.

Also, HTTP headers are case-insensitive, so, you can declare them with standard Python style (also known as "snake_case").

      builder.build()
    }.also { expected ->
      assertThat(expected.message).isEqualTo("Null interceptor: [null]")
    }
  }

  @Test fun nullNetworkInterceptorInList() {
    val builder = OkHttpClient.Builder()
    builder.networkInterceptors().addAll(listOf(null) as List<Interceptor>)
    assertFailsWith<IllegalStateException> {
      builder.build()
    }.also { expected ->

## Mix `Path`, `Query` and body parameters { #mix-path-query-and-body-parameters }

First, of course, you can mix `Path`, `Query` and request body parameter declarations freely and **FastAPI** will know what to do.

And you can also declare body parameters as optional, by setting the default to `None`:

{* ../../docs_src/body_multiple_params/tutorial001_an_py310.py hl[18:20] *}

/// note