admin = "admin"
        user = "user"

    class OtherRole(str, Enum): ...

    class User(BaseModel):
        username: str
        role: PlatformRole | OtherRole

    @app.get("/users")
    async def get_user() -> User:
        return {"username": "alice", "role": "admin"}

    client = TestClient(app)
    return client


@needs_py310
def test_get(client: TestClient):
    response = client.get("/users")

 *
 * @author mbechler
 */
public interface CommonServerMessageBlockResponse extends CommonServerMessageBlock, Response {

    /**
     * Checks if this is an asynchronous response.
     *
     * @return is an async response
     */
    boolean isAsync();

    /**
     *
     * @return the next response
     */
    @Override
    CommonServerMessageBlockResponse getNextResponse();

    /**

initial_fake_database = {"rick": "Rick Sanchez"}

fake_database = initial_fake_database.copy()

initial_state = {"except": False, "finally": False}

state = initial_state.copy()

app = FastAPI()


async def get_database():
    temp_database = fake_database.copy()
    try:
        yield temp_database
        fake_database.update(temp_database)
    except HTTPException:
        state["except"] = True
        raise

Bu durumda, bu bir `async` fonksiyondur.

---

Bunu `async def` yerine normal bir fonksiyon olarak da tanımlayabilirsiniz:

{* ../../docs_src/first_steps/tutorial003_py310.py hl[7] *}

/// note | Not

Eğer farkı bilmiyorsanız, [Async: *"Aceleniz mi var?"*](../async.md#in-a-hurry) sayfasına bakın.

///

**FastAPI** 會為你建立 `BackgroundTasks` 物件，並以該參數傳入。

## 建立任務函式 { #create-a-task-function }

建立一個作為背景任務執行的函式。

它只是個可接收參數的一般函式。

它可以是 `async def`，也可以是一般的 `def`，**FastAPI** 都能正確處理。

在此例中，任務函式會寫入檔案（模擬寄送電子郵件）。

由於寫入操作未使用 `async` 與 `await`，因此以一般的 `def` 定義該函式：

{* ../../docs_src/background_tasks/tutorial001_py310.py hl[6:9] *}

## 新增背景任務 { #add-the-background-task }

	eventsSkipped     atomic.Int64
	eventsErrorsTotal atomic.Int64

	sync.RWMutex
	targets map[TargetID]Target
	queue   chan asyncEvent
	ctx     context.Context

	statLock    sync.RWMutex
	targetStats map[TargetID]targetStat
}

type targetStat struct {
	// The number of concurrent async Send calls per targets
	currentSendCalls int64
	// The number of total events per target
	totalEvents int64

It is just a standard function that can receive parameters.

It can be an `async def` or normal `def` function, **FastAPI** will know how to handle it correctly.

In this case, the task function will write to a file (simulating sending an email).

And as the write operation doesn't use `async` and `await`, we define the function with normal `def`:

{* ../../docs_src/background_tasks/tutorial001_py310.py hl[6:9] *}

//// tab | Python 3.10+

```Python hl_lines="1"
async def needy_dependency(fresh_value: Annotated[str, Depends(get_value, use_cache=False)]):
    return {"fresh_value": fresh_value}
```

////

//// tab | Python 3.10+ 비 Annotated

/// tip | 팁

가능하다면 `Annotated` 버전을 사용하는 것을 권장합니다.

///

```Python hl_lines="1"
async def needy_dependency(fresh_value: str = Depends(get_value, use_cache=False)):

//// tab | Python 3.10+

```Python hl_lines="1"
async def needy_dependency(fresh_value: Annotated[str, Depends(get_value, use_cache=False)]):
    return {"fresh_value": fresh_value}
```

////

//// tab | Python 3.10+ 未使用 Annotated

/// tip

若可行，建議使用 `Annotated` 的版本。

///

```Python hl_lines="1"
async def needy_dependency(fresh_value: str = Depends(get_value, use_cache=False)):

from pydantic import BaseModel

app = FastAPI()


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


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Annotated[
        Item,
        Body(
            openapi_examples={
                "normal": {
                    "summary": "A normal example",