## タスク関数の作成

バックグラウンドタスクとして実行される関数を作成します。

これは、パラメーターを受け取ることができる単なる標準的な関数です。

これは `async def` または通常の `def` 関数であり、**FastAPI** はこれを正しく処理します。

ここで、タスク関数はファイル書き込みを実行します (メール送信のシミュレーション)。

また、書き込み操作では `async` と `await` を使用しないため、通常の `def` で関数を定義します。

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

## バックグラウンドタスクの追加

*path operations 関数* 内で、`.add_task()` メソッドを使用してタスク関数を *background tasks* オブジェクトに渡します。

      super(16);
    }

    private boolean finished = false;

    /*
     * This trick allows us to avoid having separate states for "first four ints" and "all other
     * four int chunks."  The state we want after the first four bytes is
     *
     * crc0 = ~int0
     * crc1 = int1
     * crc2 = int2
     * crc3 = int3
     *
     * ...so we set crc0 so that computeForWord(crc0) = -1 and xoring it with the first int

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] *}

## Add the background task { #add-the-background-task }

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] *}

## Adicione a tarefa em segundo plano { #add-the-background-task }

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            super.process(consumer);
            latch.countDown();
        }

        @Override
        public void waitForProcessed() throws InterruptedException {
            latch.await();
        }
    }

def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

<details markdown="1">
<summary>O usa <code>async def</code>...</summary>

Si tu código usa `async` / `await`, usa `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"}

def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

<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"}

def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

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

Se seu código utiliza `async` / `await`, use `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"}