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"
{!../../docs_src/background_tasks/tutorial001.py!}
```

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] *}

## Add the background task

		ACB_PWNOTREQ               = 0x00000004, /* 1 = User password not required */
		ACB_TEMPDUP                = 0x00000008, /* 1 = Temporary duplicate account */
		ACB_NORMAL                 = 0x00000010, /* 1 = Normal user account */
		ACB_MNS                    = 0x00000020, /* 1 = MNS logon user account */
		ACB_DOMTRUST               = 0x00000040, /* 1 = Interdomain trust account */

value="<font face="Roboto" data-font-src="https://fonts.googleapis.com/css?family=Roboto" style="font-size: 24px ; font-weight: normal">Another app</font><font face="Roboto" data-font-src="https://fonts.googleapis.com/css?family=Roboto" style="font-size: 24px ; font-weight: normal">: another.example.com</font>" style="rounded=0;whiteSpace=wrap;html=1;fontStyle=1;strokeWidth=4;fillColor=#dae8fc;strokeColor=#6c8ebf;" parent="1"...

 * bound. However, it would also let them create `new TypeParameter<@Nullable T>() {}`, which
 * wouldn't behave as users might expect. Additionally, it's not clear how the TypeToken API could
 * support even a "normal" `TypeParameter<T>` when `<T>` has a nullable bound. (See the discussion
 * on TypeToken.where.) So, in the interest of failing fast and encouraging the user to switch to a

Si tienes bastante conocimiento técnico (coroutines, threads, bloqueos, etc.) y tienes curiosidad acerca de cómo FastAPI gestiona `async def` vs `def` normal, continúa.

///

### Path operation functions

    serverWriter.writeMessageFrame(OPCODE_BINARY, payload)
    assertData("8232")
    assertData(payload)
  }

  @Test fun serverMessageLengthShort() {
    // Create a payload which will overflow the normal payload byte size.
    val payload = Buffer()
    while (payload.completeSegmentByteCount() <= PAYLOAD_BYTE_MAX) {
      payload.writeByte('0'.code)
    }

		ACB_PWNOTREQ               = 0x00000004, /* 1 = User password not required */
		ACB_TEMPDUP                = 0x00000008, /* 1 = Temporary duplicate account */
		ACB_NORMAL                 = 0x00000010, /* 1 = Normal user account */
		ACB_MNS                    = 0x00000020, /* 1 = MNS logon user account */
		ACB_DOMTRUST               = 0x00000040, /* 1 = Interdomain trust account */

```Python hl_lines="2  12  15-18"
{!../../docs_src/app_testing/tutorial001.py!}
```

/// tip

Notice that the testing functions are normal `def`, not `async def`.

And the calls to the client are also normal calls, not using `await`.

This allows you to use `pytest` directly without complications.

///

/// note | "Technical Details"

 * bound. However, it would also let them create `new TypeParameter<@Nullable T>() {}`, which
 * wouldn't behave as users might expect. Additionally, it's not clear how the TypeToken API could
 * support even a "normal" `TypeParameter<T>` when `<T>` has a nullable bound. (See the discussion
 * on TypeToken.where.) So, in the interest of failing fast and encouraging the user to switch to a