例えば、以下のような`main.py`ファイルを用意します:

```Python hl_lines="3"
import os

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

/// tip | 豆知識

[`os.getenv()`](https://docs.python.org/3.8/library/os.html#os.getenv) の第2引数は、返されるデフォルト値です。

指定しない場合、デフォルトは`None`ですが、ここでは使用するデフォルト値として`"World"`を指定しています。

///

次に、このPythonプログラムを呼び出します。

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

    app = FastAPI()

    client = TestClient(app)

    @app.get("/")
    async def get(
        current_user: Annotated[DummyUser | None, Depends(get_current_user)],
    ) -> str:
        return "hello world"

    response = client.get("/")

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


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

hello world dir/bar foo readonly important...

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

            String originalString = "Hello World Test";
            byte[] allBytes = originalString.getBytes(StandardCharsets.UTF_16LE);
            int partialLength = "Hello World".getBytes(StandardCharsets.UTF_16LE).length;

            // When
            String result = Strings.fromUNIBytes(allBytes, 0, partialLength);

            // Then
            assertEquals("Hello World", result, "Should decode partial byte array correctly");

Garbage collection is the big problem.  It is fine for the Go world to
have pointers into the C world and to free those pointers when they
are no longer needed.  To help, the Go code can define Go objects
holding the C pointers and use runtime.SetFinalizer on those Go objects.

It is much more difficult for the C world to have pointers into the Go
world, because the Go garbage collector is unaware of the memory

  /**
   * Flush a {@link Flushable}, with control over whether an {@code IOException} may be thrown.
   *
   * <p>If {@code swallowIOException} is true, then we don't rethrow {@code IOException}, but merely
   * log it.
   *
   * @param flushable the {@code Flushable} object to be flushed.
   * @param swallowIOException if true, don't propagate IO exceptions thrown by the {@code flush}
   *     method

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