```python
from asyncer import asyncify
from fastapi import FastAPI

app = FastAPI()


def do_blocking_work(name: str) -> str:
    # Some blocking I/O operation
    return f"Hello {name}"


@app.get("/items/")
async def read_items():
    result = await asyncify(do_blocking_work)(name="World")
    return {"message": result}
```

Dans ce cas, vous pourriez vouloir documenter à quoi cette API externe devrait ressembler. Quel *chemin d'accès* elle devrait avoir, quel corps elle devrait attendre, quelle réponse elle devrait renvoyer, etc.

## Une application avec des callbacks { #an-app-with-callbacks }

Voyons tout cela avec un exemple.

    assertThat(Buffer().writeByte(0xc0).isProbablyUtf8(16L)).isFalse()
  }

  @Test fun doesNotConsumeBuffer() {
    val buffer = Buffer()
    buffer.writeUtf8("hello ".repeat(1024))
    assertThat(buffer.isProbablyUtf8(100L)).isTrue()
    assertThat(buffer.readUtf8()).isEqualTo("hello ".repeat(1024))
  }

  /** Confirm [isProbablyUtf8] doesn't attempt to read the entire stream. */
  @Test fun doesNotReadEntireSource() {

你可以發送如下的請求：

```json
{
    "description": "Some data",
    "data": "aGVsbG8="
}
```

/// tip

`aGVsbG8=` 是 `hello` 的 base64 編碼。

///

接著 Pydantic 會將該 base64 字串解碼，並在模型的 `data` 欄位中提供原始位元組。

你會收到類似以下的回應：

```json
{
  "description": "Some data",
  "content": "hello"
}
```

## Pydantic `bytes` 用於輸出資料 { #pydantic-bytes-for-output-data }

        .Builder()
        .body("hello, Apache HttpClient 5.x")
        .build(),
    )

    val request = HttpGet(server.url("/").toUri())
    request.addHeader("Accept", "text/plain")

    @Suppress("DEPRECATION")
    httpClient.execute(request).use { response ->
      assertThat(response.code).isEqualTo(200)
      assertThat(EntityUtils.toString(response.entity)).isEqualTo("hello, Apache HttpClient 5.x")
    }

////

## Blocs de code { #code-blocks }

//// tab | Test

Un exemple de code Bash ...

```bash
# Afficher un message de bienvenue à l'univers
echo "Hello universe"
```

... et un exemple de code console ...

```console
$ <font color="#4E9A06">fastapi</font> run <u style="text-decoration-style:solid">main.py</u>

Hello World!...

hello world dir/bar foo readonly important...

그리고 나머지는 **FastAPI**에 의해 처리됩니다.

실행하고 [http://localhost:8000/v1/](http://localhost:8000/v1/)로 이동하면 Flask의 응답을 볼 수 있습니다:

```txt
Hello, World from Flask!
```

그리고 [http://localhost:8000/v2](http://localhost:8000/v2)로 이동하면 **FastAPI**의 응답을 볼 수 있습니다:

```JSON
{
    "message": "Hello World"
}

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
async def read_main():