class ReviewNode(BaseModel):
    author: Author | None = None
    state: str


class Reviews(BaseModel):
    nodes: list[ReviewNode]


class PullRequestNode(BaseModel):
    number: int
    labels: Labels
    author: Author | None = None
    title: str
    createdAt: datetime
    lastEditedAt: datetime | None = None
    updatedAt: datetime | None = None
    state: str
    reviews: Reviews

예를 들어, 어떤 값이 `str` 또는 `None`이 될 수 있다고 선언할 수 있습니다:

```python
from typing import Union


def say_hi(name: Union[str, None]):
        print(f"Hi {name}!")
```

`typing`에는 `None`이 될 수 있음을 선언하는 축약형으로 `Optional`도 있습니다.

아주 개인적인 관점에서의 팁입니다:

- 🚨 `Optional[SomeType]` 사용은 피하세요
- 대신 ✨ **`Union[SomeType, None]`를 사용하세요** ✨.

# Without aliases


@app.post("/optional-list-str", operation_id="optional_list_str")
async def read_optional_list_str(
    p: Annotated[list[str] | None, Body(embed=True)] = None,
):
    return {"p": p}


class BodyModelOptionalListStr(BaseModel):
    p: list[str] | None = None


@app.post("/model-optional-list-str", operation_id="model_optional_list_str")
async def read_model_optional_list_str(p: BodyModelOptionalListStr):

def test_raises_pydantic_v1_model_in_endpoint_param() -> None:
    class ParamModelV1(BaseModel):
        name: str

    app = FastAPI()

    with pytest.raises(PydanticV1NotSupportedError):

        @app.post("/param")
        def endpoint(data: ParamModelV1):  # pragma: no cover
            return data


def test_raises_pydantic_v1_model_in_return_type() -> None:
    class ReturnModelV1(BaseModel):
        name: str

# Without aliases


@app.get("/optional-str")
async def read_optional_str(p: Annotated[str | None, Header()] = None):
    return {"p": p}


class HeaderModelOptionalStr(BaseModel):
    p: str | None = None


@app.get("/model-optional-str")
async def read_model_optional_str(p: Annotated[HeaderModelOptionalStr, Header()]):
    return {"p": p.p}

    print("LLM translatable languages:", translatable_langs)
    return translatable_langs


@app.command()
def llm_translatable_json(
    language: Annotated[str | None, typer.Option(envvar="LANGUAGE")] = None,
) -> None:
    translatable_langs = get_llm_translatable()
    if language:
        if language in translatable_langs:
            print(json.dumps([language]))
            return
        else:

            """
        ),
    ] = None
    event: Annotated[
        str | None,
        Doc(
            """
            Optional event type name.

            Maps to `addEventListener(event, ...)` on the browser. When omitted,
            the browser dispatches on the generic `message` event.
            """
        ),
    ] = None
    id: Annotated[
        str | None,
        AfterValidator(_check_id_no_null),

						<div class="d-sm-none"></div>
						<span class="d-none d-sm-inline-block">&nbsp;</span>
						<la:message key="labels.search_result_size"
							arg0="${fe:formatFileSize(doc.content_length)}" />
					</c:if>
					<c:if test="${searchLogSupport && doc.click_count!=null && doc.click_count>0}">
						<div class="d-sm-none"></div>
						<span class="d-none d-sm-inline-block">&nbsp;</span>

            ),
        ],
        scheme_name: Annotated[
            str | None,
            Doc(
                """
                Security scheme name.

                It will be included in the generated OpenAPI (e.g. visible at `/docs`).
                """
            ),
        ] = None,
        description: Annotated[
            str | None,
            Doc(
                """

from fastapi import FastAPI
from fastapi.testclient import TestClient

app = FastAPI()


@dataclass
class Item:
    name: str
    date: datetime
    price: float | None = None
    owner_ids: list[int] | None = None


@app.get("/items/valid", response_model=Item)
def get_valid():
    return {"name": "valid", "date": datetime(2021, 7, 26), "price": 1.0}


@app.get("/items/object", response_model=Item)