Если вы запустите это и перейдёте по [http://localhost:8000/v1/](http://localhost:8000/v1/), вы увидите HTTP‑ответ от Flask:

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

А если вы перейдёте по [http://localhost:8000/v2](http://localhost:8000/v2), вы увидите HTTP‑ответ от FastAPI:

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

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip | Dica

O segundo argumento para [`os.getenv()`](https://docs.python.org/3.8/library/os.html#os.getenv) é o valor padrão a ser retornado.

Se não for fornecido, é `None` por padrão, Aqui fornecemos `"World"` como o valor padrão a ser usado.

///

Si vous l'exécutez et allez à [http://localhost:8000/v1/](http://localhost:8000/v1/) vous verrez la réponse de Flask :

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

Et si vous allez à [http://localhost:8000/v2](http://localhost:8000/v2) vous verrez la réponse de FastAPI :

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

Se você rodar a aplicação e ir até [http://localhost:8000/v1/](http://localhost:8000/v1/), você verá o retorno do Flask:

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

E se você for até [http://localhost:8000/v2](http://localhost:8000/v2), você verá o retorno do FastAPI:

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

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

Und wenn Sie auf [http://localhost:8000/v2](http://localhost:8000/v2) gehen, sehen Sie die Response von FastAPI:

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

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip | Consejo

El segundo argumento de [`os.getenv()`](https://docs.python.org/3.8/library/os.html#os.getenv) es el valor por defecto a retornar.

Si no se proporciona, es `None` por defecto; aquí proporcionamos `"World"` como el valor por defecto para usar.

///

        () -> {
          AbstractFuture<String> future = setFutureFuture.get();
          setFutureSetSuccess.set(currentFuture.get().setFuture(future));
          setFutureCompletionSuccess.set(future.set("hello-async-world"));
          awaitUnchecked(barrier);
        };
    Set<Object> finalResults = Collections.synchronizedSet(Sets.newIdentityHashSet());
    Runnable collectResultsRunnable =
        () -> {
          try {

* Create an empty file `__init__.py`.
* Create a `main.py` file with:

```Python
from fastapi import FastAPI

app = FastAPI()


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


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

### Dockerfile { #dockerfile }

    ],
    root_path="/api/v1",
    root_path_in_servers=False,
)


@app.get("/app")
def read_main(request: Request):

field after it, and fortunately was just in time to see it pop
down a large rabbit-hole under the hedge.

  In another moment down went Alice after it, never once
considering how in the world she was to get out again.

  The rabbit-hole went straight on like a tunnel for some way,
and then dipped suddenly down, so suddenly that Alice had not a
moment to think about stopping herself before she found herself