"loc": ["header", "x-token"],
                    "msg": "Field required",
                    "input": None,
                },
                {
                    "type": "missing",
                    "loc": ["header", "x-key"],
                    "msg": "Field required",
                    "input": None,
                },
            ]
        }
    ) | IsDict(
        # TODO: remove when deprecating Pydantic v1

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float = 10.5


items = {
    "foo": {"name": "Foo", "price": 50.2},
    "bar": {"name": "Bar", "description": "The Bar fighters", "price": 62, "tax": 20.2},
    "baz": {
        "name": "Baz",
        "description": "There goes my baz",

 *
 */
@Deprecated
public final class ArtifactStatus implements Comparable<ArtifactStatus> {
    /**
     * No trust - no information about status.
     */
    public static final ArtifactStatus NONE = new ArtifactStatus("none", 0);

    /**
     * No trust - information was generated with defaults.
     */
    public static final ArtifactStatus GENERATED = new ArtifactStatus("generated", 1);

    /**

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]` é na verdade um atalho para `Union[Something, None]`, eles são equivalentes.

Isso também significa que no Python 3.10, você pode utilizar `Something | None`:

//// tab | Python 3.10+

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

                    "loc": ["body", "grant_type"],
                    "msg": "Field required",
                    "input": None,
                },
                {
                    "type": "missing",
                    "loc": ["body", "username"],
                    "msg": "Field required",
                    "input": None,
                },
                {
                    "type": "missing",

     */
    @InputFile
    @PathSensitive(PathSensitivity.NONE)
    public abstract RegularFileProperty getHtmlFile();

    /**
     * The decorated HTML file
     */
    @OutputFile
    public abstract RegularFileProperty getDestinationFile();

    /**
     * JQuery used by the added decoration
     */
    @InputFiles
    @PathSensitive(PathSensitivity.NONE)
    public abstract ConfigurableFileCollection getJquery();

        """
        if self.cid is not None:
            fetcher = self._create_credentials_fetcher()
            return RefreshableCredentials.create_from_metadata(
                metadata=fetcher(),
                refresh_using=fetcher,
                method=self.METHOD,
            )
        else:
            return None

    def _create_credentials_fetcher(self):
        method = self.METHOD

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):

    "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: