"hadde", "hun", "nå", "over", "da", "ved", "fra", "du", "ut", "sin", "dem", "oss", "opp", "man", "kan", "hans", "hvor", "eller", "hva", "skal", "selv", "sjøl", "her", "alle", "vil", "bli", "ble", "blei", "blitt", "kunne", "inn", "når", "være", "kom", "noen", "noe", "ville", "dere", "som", "deres", "kun", "ja", "etter", "ned", "skulle", "denne", "for", "deg", "si", "sine", "sitt", "mot", "å", "meget", "hvorfor", "dette", "disse", "uten", "hvordan", "ingen", "din", "ditt", "blir", "samme", "hvilken", "hvilke",...

"hadde", "hun", "nå", "over", "da", "ved", "fra", "du", "ut", "sin", "dem", "oss", "opp", "man", "kan", "hans", "hvor", "eller", "hva", "skal", "selv", "sjøl", "her", "alle", "vil", "bli", "ble", "blei", "blitt", "kunne", "inn", "når", "være", "kom", "noen", "noe", "ville", "dere", "som", "deres", "kun", "ja", "etter", "ned", "skulle", "denne", "for", "deg", "si", "sine", "sitt", "mot", "å", "meget", "hvorfor", "dette", "disse", "uten", "hvordan", "ingen", "din", "ditt", "blir", "samme", "hvilken", "hvilke",...

def get_lang_paths() -> list[Path]:
    return sorted(docs_path.iterdir())


def lang_callback(lang: str | None) -> str | None:
    if lang is None:
        return None
    lang = lang.lower()
    return lang


def complete_existing_lang(incomplete: str):
    lang_path: Path
    for lang_path in get_lang_paths():

    file: Annotated[
        BinaryIO,
        Doc("The standard Python file object (non-async)."),
    ]
    filename: Annotated[str | None, Doc("The original file name.")]
    size: Annotated[int | None, Doc("The size of the file in bytes.")]
    headers: Annotated[Headers, Doc("The headers of the request.")]
    content_type: Annotated[
        str | None, Doc("The content type of the request, from the headers.")
    ]

    async def write(

</div>

Cela signifie qu'il aura **toujours une valeur**, simplement, parfois la valeur pourra être `None` (ou `null` en JSON).

Cela signifie que les clients utilisant votre API n'ont pas à vérifier si la valeur existe ou non, ils peuvent **supposer que le champ sera toujours présent**, mais que, dans certains cas, il aura la valeur par défaut `None`.

app = FastAPI()

oauth2_scheme = OAuth2AuthorizationCodeBearer(
    authorizationUrl="authorize", tokenUrl="token", auto_error=True
)


@app.get("/items/")
async def read_items(token: str | None = Security(oauth2_scheme)):
    return {"token": token}


client = TestClient(app)


def test_no_token():
    response = client.get("/items")
    assert response.status_code == 401, response.text

oauth2_scheme = OAuth2AuthorizationCodeBearer(
    authorizationUrl="authorize",
    tokenUrl="token",
    description="OAuth2 Code Bearer",
    auto_error=True,
)


@app.get("/items/")
async def read_items(token: str | None = Security(oauth2_scheme)):
    return {"token": token}


client = TestClient(app)


def test_no_token():
    response = client.get("/items")
    assert response.status_code == 401, response.text

/// note | Remarque

**FastAPI** saura que la valeur de `q` n'est pas requise grâce à la valeur par défaut `= None`.

L'annotation de type `str | None` n'est pas utilisée par **FastAPI** pour déterminer que la valeur n'est pas requise, il le saura parce qu'elle a une valeur par défaut `= None`.

Mais ajouter ces annotations de type permettra à votre éditeur de vous offrir un meilleur support et de détecter des erreurs.

## Optional parameters { #optional-parameters }

The same way, you can declare optional query parameters, by setting their default to `None`:

{* ../../docs_src/query_params/tutorial002_py310.py hl[7] *}

In this case, the function parameter `q` will be optional, and will be `None` by default.

/// check

    code_block: list[str] = []
    for line_a, line_b in zip(block_a["content"], block_b["content"], strict=False):
        line_a_comment: str | None = None
        line_b_comment: str | None = None

        # Handle comments based on language
        if block_language in {
            "python",
            "py",
            "sh",
            "bash",
            "dockerfile",