예를 들어 다음과 같은 `main.py` 파일이 있다고 합시다:

```Python hl_lines="3"
import os

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

/// tip | 팁

<a href="https://docs.python.org/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> 의 두 번째 인자는 반환할 기본값입니다.

여기서는 `"World"`를 넣었기에 기본값으로써 사용됩니다. 넣지 않으면 `None` 이 기본값으로 사용됩니다.

///

그러면 해당 파이썬 프로그램을 다음과 같이 호출할 수 있습니다:

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

E se você for até <a href="http://localhost:8000/v2" class="external-link" target="_blank">http://localhost:8000/v2</a>, você verá o retorno do 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 <a href="https://docs.python.org/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> 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.

///

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

Und wenn Sie auf <a href="http://localhost:8000/v2" class="external-link" target="_blank">http://localhost:8000/v2</a> gehen, sehen Sie die Response von FastAPI:

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

 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.maven.embedder;

/**
 * Hello world!
 *
 */
public class App
{
    public static void main( String[] args )
    {
        System.out.println( "Hello World!" );
    }

例如，你可以创建一个名为 `main.py` 的文件，其中包含以下内容：

```Python hl_lines="3"
import os

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

/// tip

第二个参数是 <a href="https://docs.python.org/zh-cn/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> 的默认返回值。

如果没有提供，默认值为 `None`，这里我们提供 `"World"` 作为默认值。

///

然后你可以调用这个 Python 程序：

//// tab | Linux, macOS, Windows Bash

@app.get("/", dependencies=[Depends(bearer_scheme)])
async def get_root():
    return {"message": "Hello, World!"}


client = TestClient(app)


def test_get_root():
    response = client.get("/", headers={"Authorization": "Bearer token"})
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Hello, World!"}


def test_get_root_no_token():
    response = client.get("/")

async def get_token(token: Annotated[str, Depends(oauth2_scheme)]) -> str:
    return token


app = FastAPI(dependencies=[Depends(get_token)])


@app.get("/")
async def root():
    return {"message": "Hello World"}


@app.get(
    "/with-oauth2-scheme",
    dependencies=[Security(oauth2_scheme, scopes=["read", "write"])],
)
async def read_with_oauth2_scheme():
    return {"message": "Admin Access"}


@app.get(

import os

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

/// tip | Совет

Второй аргумент <a href="https://docs.python.org/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> - это возвращаемое по умолчанию значение.

Если значение не указано, то по умолчанию оно равно `None`. В данном случае мы указываем `«World»` в качестве значения по умолчанию.

///

Hello World!...