Це звичайна функція, яка може отримувати параметри.

Вона може бути асинхронною `async def` або звичайною `def` функцією – **FastAPI** обробить її правильно.

У нашому випадку функція записує у файл (імітуючи надсилання email).

І оскільки операція запису не використовує `async` та `await`, ми визначаємо функцію як звичайну `def`:

{* ../../docs_src/background_tasks/tutorial001.py hl[6:9] *}

## Додавання фонової задачі

async def dep0(response: Response):
    response.headers["x-level0"] = "True"


async def dep1(response: Response):
    response.headers["x-level1"] = "True"


async def dep2(response: Response):
    response.headers["x-level2"] = "True"


async def dep3(response: Response):
    response.headers["x-level3"] = "True"


async def dep4(response: Response):

app = FastAPI()


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


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

<details markdown="1">
<summary>或者使用 <code>async def</code>...</summary>

如果你的代码里会出现 `async` / `await`，请使用 `async def`：

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

    assertThat(response1.body.source().readUtf8(3)).isEqualTo("ABC")
    assertThat(response2.body.source().readUtf8(3)).isEqualTo("GHI")
    assertThat(response1.body.source().readUtf8(3)).isEqualTo("DEF")
    assertThat(response2.body.source().readUtf8(3)).isEqualTo("JKL")
    val c0e0 = server.takeRequest()
    assertThat(c0e0.connectionIndex).isEqualTo(0)
    assertThat(c0e0.exchangeIndex).isEqualTo(0)

This is necessary on Windows, because some applications do not understand/handle
Linux-like paths MSYS uses, for example, Docker.
"""

import argparse
import os


def should_convert(var_name: str,
                   blacklist: list[str] | None,
                   whitelist_prefix: list[str] | None):
  """Check the variable name against white/black lists."""

///

### `Response` { #response }

A classe principal de respostas, todas as outras respostas herdam dela.

Você pode retorná-la diretamente.

Ela aceita os seguintes parâmetros:

* `content` - Uma sequência de caracteres (`str`) ou `bytes`.
* `status_code` - Um código de status HTTP do tipo `int`.

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_py39.py hl[6:9] *}

É apenas uma função padrão que pode receber parâmetros.

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

Neste caso, a função da tarefa escreverá em um arquivo (simulando o envio de um e-mail).

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

{* ../../docs_src/background_tasks/tutorial001_py39.py hl[6:9] *}

Elle peut être une fonction asynchrone (`async def`) ou une fonction normale (`def`), **FastAPI** saura la gérer correctement.

Dans cet exemple, la fonction de tâche écrira dans un fichier (afin de simuler un envoi d'email).

L'opération d'écriture n'utilisant ni `async` ni `await`, on définit la fonction avec un `def` normal.

{* ../../docs_src/background_tasks/tutorial001.py hl[6:9] *}

import base64, hashlib, sys
from mercurial import registrar, ui, hg, node
from mercurial.i18n import _
cmdtable = {}
command = registrar.command(cmdtable)
@command(b'goreposum', [], _('url'), norepo=True)
def goreposum(ui, url):
  """
  goreposum computes a checksum of all the named state in the remote repo.
  It hashes together all the branch names and hashes
  and then all the bookmark names and hashes.