app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: Union[bool, None] = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}


@app.put("/items/{item_id}")
def update_item(item_id: int, item: Item):

`Optional[Something]` is actually a shortcut for `Union[Something, None]`, they are equivalent.

This also means that in Python 3.10, you can use `Something | None`:

//// tab | Python 3.10+

```Python hl_lines="1"
{!> ../../docs_src/python_types/tutorial009_py310.py!}
```

    "bar": {"id": "bar", "title": "Bar", "description": "The bartenders"},
}

app = FastAPI()


class Item(BaseModel):
    id: str
    title: str
    description: Union[str, None] = None


@app.get("/items/{item_id}", response_model=Item)
async def read_main(item_id: str, x_token: str = Header()):
    if x_token != fake_secret_token:

		{xForwardedFor, "", ""},                                                       // None
		{xRealIP, "8.8.8.8", "8.8.8.8"},                                               // Single address
		{xRealIP, "[2001:db8:cafe::17]:4711", "[2001:db8:cafe::17]"},                  // IPv6 address
		{xRealIP, "", ""},                                                             // None
		{forwarded, `for="_gazonk"`, "_gazonk"},                                       // Hostname

    assertSame(CharMatcher.any(), CharMatcher.none().negate());
    assertSame(CharMatcher.none(), CharMatcher.any().negate());

    assertSame(WHATEVER, CharMatcher.any().and(WHATEVER));
    assertSame(CharMatcher.any(), CharMatcher.any().or(WHATEVER));

    assertSame(CharMatcher.none(), CharMatcher.none().and(WHATEVER));
    assertSame(WHATEVER, CharMatcher.none().or(WHATEVER));
  }

    "bar": {"id": "bar", "title": "Bar", "description": "The bartenders"},
}

app = FastAPI()


class Item(BaseModel):
    id: str
    title: str
    description: str | None = None


@app.get("/items/{item_id}", response_model=Item)
async def read_main(item_id: str, x_token: Annotated[str, Header()]):
    if x_token != fake_secret_token:

from fastapi import FastAPI
from fastapi.openapi.docs import (
    get_redoc_html,
    get_swagger_ui_html,
    get_swagger_ui_oauth2_redirect_html,
)

app = FastAPI(docs_url=None, redoc_url=None)


@app.get("/docs", include_in_schema=False)
async def custom_swagger_ui_html():
    return get_swagger_ui_html(
        openapi_url=app.openapi_url,
        title=app.title + " - Swagger UI",

    rules:
      - apiGroups:
          - ""
        apiVersions:
          - v1
        operations:
          - CREATE
        resources:
          - pods
        scope: '*'
    sideEffects: None
    timeoutSeconds: 10
  - admissionReviewVersions:
      - v1beta1
      - v1
    clientConfig:
      service:
        name: istiod
        namespace: istio-system
        path: /inject
        port: 443

    return {"item_id": item_id, "item": item}


@app.head("/items/{item_id}")
def head_item(item_id: str):
    return JSONResponse(None, headers={"x-fastapi-item-id": item_id})


@app.options("/items/{item_id}")
def options_item(item_id: str):
    return JSONResponse(None, headers={"x-fastapi-item-id": item_id})


@app.patch("/items/{item_id}")
def patch_item(item_id: str, item: Item):

        width: 300px;
        height: 50px;
        padding: 2px;
        font-family: Verdana, sans-serif;
        font-size: 10pt;
        color: #000000;
        text-decoration: none;
    }
    a.plain {
        display: inline;
        float: none;
        width: auto;
        height: auto;
    }
    a.sort {
        display: block;
        float: left;
        width: 100px;
        height: 15px;