host: str
    save_data: bool
    if_modified_since: str | None = None
    traceparent: str | None = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(headers: Annotated[CommonHeaders, Header()]):

    assert response.status_code == 401, response.text
    assert response.json() == {"detail": "Not authenticated"}
    assert response.headers["WWW-Authenticate"] == "Bearer"


@needs_py39
def test_token(client: TestClient):
    response = client.get("/items", headers={"Authorization": "Bearer testtoken"})
    assert response.status_code == 200, response.text
    assert response.json() == {"token": "testtoken"}

Each HTTP request contains a URL, a method (like `GET` or `POST`), and a list of headers. Requests may also contain a body: a data stream of a specific content type.

## [Responses](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-response/)

The response answers the request with a code (like 200 for success or 404 for not found), headers, and its own optional body.

## Rewriting Requests

import okhttp3.internal.http2.Header
import okio.ByteString

/**
 * Representation of an individual case (set of headers and wire format). There are many cases for a
 * single story.  This class is used reflectively with Moshi to parse stories.
 */
data class Case(
  val seqno: Int = 0,
  val wire: ByteString? = null,
  val headers: List<Map<String, String>>,
) : Cloneable {
  val headersList: List<Header>
    get() {

    host: str
    save_data: bool
    if_modified_since: str | None = None
    traceparent: str | None = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(headers: Annotated[CommonHeaders, Header()]):

package com.google.common.collect.testing;

import static com.google.common.collect.testing.testers.CollectionSpliteratorTester.getSpliteratorNotImmutableCollectionAllowsAddMethod;
import static com.google.common.collect.testing.testers.CollectionSpliteratorTester.getSpliteratorNotImmutableCollectionAllowsRemoveMethod;
import static com.google.common.collect.testing.testers.ListListIteratorTester.getListIteratorFullyModifiableMethod;

    save_data: bool
    if_modified_since: Union[str, None] = None
    traceparent: Union[str, None] = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(headers: CommonHeaders = Header()):

{!../../docs_src/python_types/tutorial009.py!}
```

Entonces puedes declarar una variable que sea de tipo `Person`:

```Python hl_lines="6"
{!../../docs_src/python_types/tutorial009.py!}
```

Una vez más tendrás todo el soporte del editor:

<img src="https://fastapi.tiangolo.com/img/python-types/image06.png">

## Modelos de Pydantic

    mod = importlib.import_module(f"docs_src.header_param_models.{request.param}")

    client = TestClient(mod.app)
    client.headers.clear()
    return client


def test_header_param_model(client: TestClient):
    response = client.get(
        "/items/",
        headers=[
            ("save-data", "true"),
            ("if-modified-since", "yesterday"),
            ("traceparent", "123"),

client = TestClient(app)


@pytest.mark.parametrize(
    "path,headers,expected_status,expected_response",
    [
        ("/items", None, 200, {"User-Agent": "testclient"}),
        ("/items", {"X-Header": "notvalid"}, 200, {"User-Agent": "testclient"}),
        ("/items", {"User-Agent": "FastAPI test"}, 200, {"User-Agent": "FastAPI test"}),
    ],
)
def test(path, headers, expected_status, expected_response):