```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.

///

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


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

client = TestClient(app)


def test_main():
    response = client.get("/app")
    assert response.status_code == 200
    assert response.json() == {"message": "Hello World", "root_path": "/api/v1"}


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200
    assert response.json() == snapshot(
        {

from fastapi import FastAPI, Request

app = FastAPI()


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

from fastapi import FastAPI, Request

app = FastAPI(root_path="/api/v1")


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

from .main import app

client = TestClient(app)


def test_read_main():
    response = client.get("/")
    assert response.status_code == 200

        {"url": "https://prod.example.com", "description": "Production environment"},
    ],
    root_path="/api/v1",
)


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

```Python
response = requests.get("http://example.com/some/url")
```

对应地，FastAPI 的 API 路径操作可能看起来是这样的：

```Python hl_lines="1"
@app.get("/some/url")
def read_url():
    return {"message": "Hello World"}
```

可以看到 `requests.get(...)` 与 `@app.get(...)` 的相似之处。

/// check | 启发 **FastAPI**：

* 提供简单直观的 API。
* 直接、自然地使用 HTTP 方法名（操作）。
* 具备合理默认值，同时支持强大定制能力。

///

client = TestClient(app, root_path="/api/v1")


def test_main():
    response = client.get("/app")
    assert response.status_code == 200
    assert response.json() == {"message": "Hello World", "root_path": "/api/v1"}


def test_openapi():
    response = client.get("/openapi.json")
    assert response.status_code == 200
    assert response.json() == snapshot(
        {
            "openapi": "3.1.0",

	type _Ctype_void [0]byte

The _cgo_gotypes.go file also contains the definitions of the
functions. They all have similar bodies that invoke runtime·cgocall
to make a switch from the Go runtime world to the system C (GCC-based)
world.

For example, here is the definition of _Cfunc_puts:

	//go:cgo_import_static _cgo_be59f0f25121_Cfunc_puts
	//go:linkname __cgofn__cgo_be59f0f25121_Cfunc_puts _cgo_be59f0f25121_Cfunc_puts