annotation: Optional[Any] = None,
        alias: Optional[str] = None,
        alias_priority: Union[int, None] = _Unset,
        # TODO: update when deprecating Pydantic v1, import these types
        # validation_alias: str | AliasPath | AliasChoices | None
        validation_alias: Union[str, None] = None,
        serialization_alias: Union[str, None] = None,
        title: Optional[str] = None,
        description: Optional[str] = None,

            """
        ),
    ] = _Unset,
    # TODO: update when deprecating Pydantic v1, import these types
    # validation_alias: str | AliasPath | AliasChoices | None
    validation_alias: Annotated[
        Union[str, None],
        Doc(
            """
            'Whitelist' validation step. The parameter field will be the single one
            allowed by the alias or set of aliases defined.

    description: Optional[str] = None
    content: Dict[str, MediaType]
    required: Optional[bool] = None


class Link(BaseModelWithConfig):
    operationRef: Optional[str] = None
    operationId: Optional[str] = None
    parameters: Optional[Dict[str, Union[Any, str]]] = None
    requestBody: Optional[Union[Any, str]] = None
    description: Optional[str] = None
    server: Optional[Server] = None

    # Get custom config for the current package, from the env var
    config: Dict[str, Any] = context.config.data["tool"]["tiangolo"][
        "_internal-slim-build"
    ]["packages"][TIANGOLO_BUILD_PACKAGE]
    project_config: Dict[str, Any] = config["project"]
    # Get main optional dependencies, extras
    optional_dependencies: Dict[str, List[str]] = metadata.get(
        "optional-dependencies", {}
    )

def get_openapi(
    *,
    title: str,
    version: str,
    openapi_version: str = "3.1.0",
    summary: Optional[str] = None,
    description: Optional[str] = None,
    routes: Sequence[BaseRoute],
    webhooks: Optional[Sequence[BaseRoute]] = None,
    tags: Optional[List[Dict[str, Any]]] = None,
    servers: Optional[List[Dict[str, Union[str, Any]]]] = None,
    terms_of_service: Optional[str] = None,

        ),
    ]


class HTTPBase(SecurityBase):
    def __init__(
        self,
        *,
        scheme: str,
        scheme_name: Optional[str] = None,
        description: Optional[str] = None,
        auto_error: bool = True,
    ):
        self.model = HTTPBaseModel(scheme=scheme, description=description)
        self.scheme_name = scheme_name or self.__class__.__name__
        self.auto_error = auto_error

⚫️ ✊ 📇 ⚗ 1️⃣ 📖 🔠 🔖.

🔠 📖 💪 🔌:

* `name` (**✔**): `str` ⏮️ 🎏 📛 👆 ⚙️ `tags` 🔢 👆 *➡ 🛠️* & `APIRouter`Ⓜ.
* `description`: `str` ⏮️ 📏 📛 🔖. ⚫️ 💪 ✔️ ✍ & 🔜 🎦 🩺 🎚.
* `externalDocs`: `dict` 🔬 🔢 🧾 ⏮️:
    * `description`: `str` ⏮️ 📏 📛 🔢 🩺.
    * `url` (**✔**): `str` ⏮️ 📛 🔢 🧾.

### ✍ 🗃 🔖

➡️ 🔄 👈 🖼 ⏮️ 🔖 `users` & `items`.

    return not (current_status_code < 200 or current_status_code in {204, 205, 304})


def get_path_param_names(path: str) -> Set[str]:
    return set(re.findall("{(.*?)}", path))


def create_response_field(
    name: str,
    type_: Type[Any],
    class_validators: Optional[Dict[str, Validator]] = None,
    default: Optional[Any] = Undefined,
    required: Union[bool, UndefinedType] = Undefined,

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

Using `Optional[str]` instead of just `str` will let the editor help you detecting errors where you could be assuming that a value is always a `str`, when it could actually be `None` too.

`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`:

=== "Python 3.10+"

```Python hl_lines="1  4"
{!../../../docs_src/python_types/tutorial009.py!}
```

Використання `Optional[str]` замість просто `str` дозволить редактору допомогти вам виявити помилки, коли ви могли б вважати, що значенням завжди є `str`, хоча насправді воно також може бути `None`.

`Optional[Something]` насправді є скороченням для `Union[Something, None]`, вони еквівалентні.

Це також означає, що в Python 3.10 ви можете використовувати `Something | None`: