其余的请求则会被 **FastAPI** 处理。

如果您使用 Uvicorn 运行应用实例并且访问 <a href="http://localhost:8000/v1/" class="external-link" target="_blank">http://localhost:8000/v1/</a>，您将会看到由 Flask 返回的响应：

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

并且如果您访问 <a href="http://localhost:8000/v2" class="external-link" target="_blank">http://localhost:8000/v2</a>，您将会看到由 FastAPI 返回的响应：

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

import pytest
from dirty_equals import IsDict
from fastapi.testclient import TestClient

from ...utils import needs_py39


@pytest.fixture(name="client")
def get_client():
    from docs_src.bigger_applications.app_an_py39.main import app

    client = TestClient(app)
    return client


@needs_py39
def test_users_token_jessica(client: TestClient):
    response = client.get("/users?token=jessica")

そのため、HTTPステータスコードが`418`で、JSONの内容が以下のような明確なエラーを受け取ることになります:

```JSON
{"message": "Oops! yolo did something. There goes a rainbow..."}
```

!!! note "技術詳細"
    また、`from starlette.requests import Request`と`from starlette.responses import JSONResponse`を使用することもできます。

    **FastAPI** は開発者の利便性を考慮して、`fastapi.responses`と同じ`starlette.responses`を提供しています。しかし、利用可能なレスポンスのほとんどはStarletteから直接提供されます。これは`Request`と同じです。

```Python hl_lines="4 6 20 21"
{!../../../docs_src/response_directly/tutorial001.py!}
```

!!! note "Detalles Técnicos"
    También puedes usar `from starlette.responses import JSONResponse`.

        * **FastAPI**: (uses Starlette) an API microframework with several additional features for building APIs, with data validation, etc.

* **Uvicorn**:
    * Will have the best performance, as it doesn't have much extra code apart from the server itself.

!!! note "Technische Details"
    Sie könnten auch `from starlette.requests import Request` verwenden.

    **FastAPI** bietet es als Komfort für Sie, den Entwickler, an. Aber es stammt direkt von Starlette.

### Vor und nach der `response`

import pytest
from dirty_equals import IsDict
from fastapi.testclient import TestClient


@pytest.fixture(name="client")
def get_client():
    from docs_src.bigger_applications.app_an.main import app

    client = TestClient(app)
    return client


def test_users_token_jessica(client: TestClient):
    response = client.get("/users?token=jessica")
    assert response.status_code == 200

    * `main:app`이 파이썬의 `import` 문법과 흡사한 면이 있다는 걸 알 수 있습니다:

        ```Python
        from main import app
        ```

    * 곧, `main:app`안에 있는 콜론의 의미는 파이썬에서 `from main import app`에서의 `import`와 같습니다.
* `--workers`: 사용할 워커 프로세스의 개수이며 숫자만큼의 유비콘 워커를 실행합니다. 이 예제에서는 4개의 워커를 실행합니다.
* `--worker-class`: 워커 프로세스에서 사용하기 위한 구니콘과 호환되는 워커클래스.

Bạn viết chuẩn Python với kiểu dữ liệu như sau:

```Python
from datetime import date

from pydantic import BaseModel

# Declare a variable as a str
# and get editor support inside the function
def main(user_id: str):
    return user_id


# A Pydantic model
class User(BaseModel):

from .param_functions import File as File
from .param_functions import Form as Form
from .param_functions import Header as Header
from .param_functions import Path as Path
from .param_functions import Query as Query
from .param_functions import Security as Security
from .requests import Request as Request
from .responses import Response as Response
from .routing import APIRouter as APIRouter