///

### Before and after the `response`

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"

    if err == nil {
        fmt.Println("Got response with field", resp["result"])
    }
```

The wrapper will handle all serialization and de-seralization of the request and response,
and furthermore provides reuse of the structs used for the request and response.

Note that Responses sent for serialization are automatically reused for similar requests.

    async_exit_stack: AsyncExitStack,
    embed_body_fields: bool,
) -> SolvedDependency:
    values: Dict[str, Any] = {}
    errors: List[Any] = []
    if response is None:
        response = Response()
        del response.headers["content-length"]
        response.status_code = None  # type: ignore
    dependency_cache = dependency_cache or {}
    sub_dependant: Dependant
    for sub_dependant in dependant.dependencies:

// when it has been returned on a handler.
// This will disable automatic response recycling/pooling.
// Typically this is used when the response sharing part of its data structure.
func (h *SingleHandler[Req, Resp]) WithSharedResponse() *SingleHandler[Req, Resp] {
	h.sharedResp = true
	return h
}

// NewResponse creates a new response.

        .url("https://api.github.com/gists/c2a7c39532239ff261be")
        .build();
    try (Response response = client.newCall(request).execute()) {
      if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

      Gist gist = gistJsonAdapter.fromJson(response.body().source());

      for (Map.Entry<String, GistFile> entry : gist.files.entrySet()) {

* Uma função `call_next` que receberá o `request` como um parâmetro.
    * Esta função passará a `request` para a *operação de rota* correspondente.
    * Então ela retorna a `response` gerada pela *operação de rota* correspondente.
* Você pode então modificar ainda mais o `response` antes de retorná-lo.

```Python hl_lines="8-9  11  14"
{!../../docs_src/middleware/tutorial001.py!}
```

/// tip | "Dica"

from fastapi import FastAPI, Response

app = FastAPI()


@app.get("/headers-and-object/")
def get_headers(response: Response):
    response.headers["X-Cat-Dog"] = "alone in the world"

    val startNanos = AtomicLong()
    newWebSocket(
      "/runCase?case=$number&agent=okhttp",
      object : WebSocketListener() {
        override fun onOpen(
          webSocket: WebSocket,
          response: Response,
        ) {
          println("Executing test case $number/$count")
          startNanos.set(System.nanoTime())
        }

        override fun onMessage(
          webSocket: WebSocket,

from fastapi import FastAPI, Response

app = FastAPI()


@app.post("/cookie-and-object/")
def create_cookie(response: Response):
    response.set_cookie(key="fakesession", value="fake-cookie-session-value")

        "404": {
            "description": "Additional Response",
            "content": {
                "application/json": {
                    "schema": {
                        "$ref": "#/components/schemas/Message"
                    }
                }
            }
        },
        "200": {
            "description": "Successful Response",
            "content": {
                "application/json": {