Teníamos esta anotación de tipo:

```Python
q: str | None = None
```

Lo que haremos es envolver eso con `Annotated`, para que se convierta en:

```Python
q: Annotated[str | None] = None
```

Ambas versiones significan lo mismo, `q` es un parámetro que puede ser un `str` o `None`, y por defecto, es `None`.

Ahora vamos a lo divertido. 🎉

from sqlmodel import Field, Session, SQLModel, create_engine, select


class Hero(SQLModel, table=True):
    id: int | None = Field(default=None, primary_key=True)
    name: str = Field(index=True)
    age: int | None = Field(default=None, index=True)
    secret_name: str


sqlite_file_name = "database.db"
sqlite_url = f"sqlite:///{sqlite_file_name}"

connect_args = {"check_same_thread": False}

def gen_dependency(value: str) -> Generator[str, None, None]:
    yield value


async def async_gen_dependency(value: str) -> AsyncGenerator[str, None]:
    yield value


class CallableDependency:
    def __call__(self, value: str) -> str:
        return value


class CallableGenDependency:
    def __call__(self, value: str) -> Generator[str, None, None]:
        yield value

We had this type annotation:

```Python
q: str | None = None
```

What we will do is wrap that with `Annotated`, so it becomes:

```Python
q: Annotated[str | None] = None
```

Both of those versions mean the same thing, `q` is a parameter that can be a `str` or `None`, and by default, it is `None`.

Now let's jump to the fun stuff. 🎉

) -> TypeGuard[type[_T]]:
    try:
        return isinstance(cls, type) and issubclass(cls, class_or_tuple)  # type: ignore[arg-type]
    except TypeError:  # pragma: no cover
        if isinstance(cls, WithArgsTypes):
            return False
        raise  # pragma: no cover


def _annotation_is_sequence(annotation: type[Any] | None) -> bool:

from inline_snapshot import snapshot


@dataclass
class Item:
    id: uuid.UUID
    name: str
    price: float
    tags: list[str] = field(default_factory=list)
    description: str | None = None
    tax: float | None = None


app = FastAPI()


@app.get("/item", response_model=Item)
async def read_item():
    return {
        "id": uuid.uuid4(),
        "name": "Island In The Moon",

}

#result .site cite {
	color: #093;
	font-style: normal;
}

#result .more {
	display: none;
}

#result .info {
	font-size: 80%;
}

#result .url-copy {
	color: #007bff;
}

#result .url-copied {
	color: #2c974b;
}

#result .favorited {
	display: none;
}

#result .favorited i {
	color: #fab005;
}

#result .thumbnail {
	width: 100px;

        elt = self.element.find('sts:{}'.format(name), _STS_NS)
        return STSElement(self.root_name, elt) if elt is not None else None

    def get_child_text(self, name, strict=True):
        """Extract text of a child element. If strict, and child element is
        not present, raises InvalidXMLError and otherwise returns
        None.

        """
        if strict:
            try:

app = FastAPI()


@app.get("/items/")
def read_items(q: str | None = Param(default=None)):  # type: ignore
    return {"q": q}


client = TestClient(app)


def test_default_param_query_none():
    response = client.get("/items/")
    assert response.status_code == 200, response.text
    assert response.json() == {"q": None}


def test_default_param_query():
    response = client.get("/items/?q=foo")

from fastapi import FastAPI
from pydantic import BaseModel


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


app = FastAPI()


@app.post("/items/")
async def create_item(item: Item):