Neste caso, é uma função `assíncrona`.

---

Você também pode defini-la como uma função normal em vez de `async def`:

```Python hl_lines="7"
{!../../docs_src/first_steps/tutorial003.py!}
```

/// note | "Nota"

Se você não sabe a diferença, verifique o [Async: *"Com pressa?"*](../async.md#com-pressa){.internal-link target=_blank}.

///

### Passo 5: retorne o conteúdo

```Python hl_lines="8"

@dataclass
class Author:
    name: str
    items: List[Item] = field(default_factory=list)  # (3)


app = FastAPI()


@app.post("/authors/{author_id}/items/", response_model=Author)  # (4)
async def create_author_items(author_id: str, items: List[Item]):  # (5)
    return {"name": author_id, "items": items}  # (6)


@app.get("/authors/", response_model=List[Author])  # (7)
def get_authors():  # (8)

<details markdown="1">
<summary>Ou utilisez <code>async def</code> ...</summary>

Si votre code utilise `async` / `await`, utilisez `async def` :

```Python hl_lines="9  14"
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
async def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")

```

<details markdown="1">
<summary>或可以使用 <code>async def</code>...</summary>

如果你的程式使用 `async` / `await`，請使用 `async def`：

```Python hl_lines="9  14"
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
async def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
async def read_item(item_id: int, q: Union[str, None] = None):

É apenas uma função padrão que pode receber parâmetros.

Pode ser uma função `async def` ou `def` normal, o **FastAPI** saberá como lidar com isso corretamente.

Nesse caso, a função de tarefa gravará em um arquivo (simulando o envio de um e-mail).

E como a operação de gravação não usa `async` e `await`, definimos a função com `def` normal:

```Python hl_lines="6-9"

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.py hl[6:9] *}

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

 *
 */

package okhttp3

import java.net.InetAddress
import java.net.UnknownHostException
import java.util.concurrent.CountDownLatch
import okio.IOException

/**
 * An async domain name service that resolves IP addresses for host names.
 *
 * The main implementations will typically be implemented using specific DNS libraries such as
 *  * Android DnsResolver
 *  * OkHttp DnsOverHttps

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package disk

import (
	"os"
	"syscall"

	"golang.org/x/sys/unix"
)

// Fdatasync - fdatasync() is similar to fsync(), but does not flush modified metadata
// unless that metadata is needed in order to allow a subsequent data retrieval
// to  be  correctly  handled.   For example, changes to st_atime or st_mtime

Es handelt sich schlicht um eine Standard-Funktion, die Parameter empfangen kann.

Es kann sich um eine `async def`- oder normale `def`-Funktion handeln. **FastAPI** weiß, wie damit zu verfahren ist.

In diesem Fall schreibt die Taskfunktion in eine Datei (den Versand einer E-Mail simulierend).

Und da der Schreibvorgang nicht `async` und `await` verwendet, definieren wir die Funktion mit normalem `def`:

```Python hl_lines="6-9"