async def read_items(
    item_id: UUID,
    start_datetime: Annotated[datetime, Body()],
    end_datetime: Annotated[datetime, Body()],
    process_after: Annotated[timedelta, Body()],
    repeat_at: Annotated[time | None, Body()] = None,
):
    start_process = start_datetime + process_after
    duration = end_datetime - start_process
    return {
        "item_id": item_id,
        "start_datetime": start_datetime,

As, by default, singular values are interpreted as query parameters, you don't have to explicitly add a `Query`, you can just do:

```Python
q: Union[str, None] = None
```

Or in Python 3.10 and above:

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

For example:

//// tab | Python 3.10+

```Python hl_lines="28"
{!> ../../docs_src/body_multiple_params/tutorial004_an_py310.py!}
```

app = FastAPI()


def write_log(message: str):
    with open("log.txt", mode="a") as log:
        log.write(message)


def get_query(background_tasks: BackgroundTasks, q: str | None = None):
    if q:
        message = f"found query: {q}\n"
        background_tasks.add_task(write_log, message)
    return q


@app.post("/send-notification/{email}")
async def send_notification(

		opCh: make(chan PartialOperation, mrfOpsQueueSize),
	}
}

// Add a partial S3 operation (put/delete) when one or more disks are offline.
func (m *mrfState) addPartialOp(op PartialOperation) {
	if m == nil {
		return
	}

	if atomic.LoadInt32(&m.closed) == 1 {
		return
	}

	m.wg.Add(1)
	defer m.wg.Done()

	if atomic.LoadInt32(&m.closing) == 1 {
		return
	}

	select {
	case m.opCh <- op:
	default:

</div>

Isso significa que ele **sempre terá um valor**, só que às vezes o valor pode ser `None` (ou `null` em termos de JSON).

Isso quer dizer que, os clientes que usam sua API não precisam verificar se o valor existe ou não, eles podem **assumir que o campo sempre estará lá**, mas que em alguns casos terá o valor padrão de `None`.

A maneira de descrever isso no OpenAPI é marcar esse campo como **obrigatório**, porque ele sempre estará lá.

		t.Skip()
	}

	type Yasuo struct {
		ID        string `gorm:"default:gen_random_uuid()"`
		Name      string
		CreatedAt time.Time `gorm:"type:TIMESTAMP WITHOUT TIME ZONE"`
		UpdatedAt time.Time `gorm:"type:TIMESTAMP WITHOUT TIME ZONE;default:current_timestamp"`
	}

	if err := DB.Exec("CREATE EXTENSION IF NOT EXISTS pgcrypto;").Error; err != nil {
		t.Errorf("Failed to create extension pgcrypto, got error %v", err)
	}

    client = TestClient(app)
    return client


@needs_py310
@pytest.mark.parametrize(
    "path,headers,expected_status,expected_response",
    [
        ("/items", None, 200, {"X-Token values": None}),
        ("/items", {"x-token": "foo"}, 200, {"X-Token values": ["foo"]}),
        # TODO: fix this, is it a bug?

from fastapi import FastAPI
from pydantic import BaseModel, EmailStr

app = FastAPI()


class UserBase(BaseModel):
    username: str
    email: EmailStr
    full_name: str | None = None


class UserIn(UserBase):
    password: str


class UserOut(UserBase):
    pass


class UserInDB(UserBase):
    hashed_password: str


def fake_password_hasher(raw_password: str):

			break
		}
	}(user.ID)

	wg.Add(1)
	go func() {
		defer wg.Done()
		<-writerFinish
		pdb.Reset()
	}()

	wg.Wait()

	if unexpectedError {
		t.Fatalf("should is a unexpected error")
	}
}

// TestPreparedStmtConcurrentClose test calling close and executing SQL concurrently
// for example: one goroutine found error and just close the database, and others are executing SQL

 * </ul>
 *
 */
@CacheableTask
abstract class UserGuideTransformTask extends DefaultTask {

    @PathSensitive(PathSensitivity.NONE)
    @InputFile
    abstract RegularFileProperty getSourceFile();

    @PathSensitive(PathSensitivity.NONE)
    @InputFile
    abstract RegularFileProperty getLinksFile();

    @OutputFile
    abstract RegularFileProperty getDestFile();

    @Input