)

app.include_router(router2_override)

app.include_router(router2_default)

client = TestClient(app)


def test_level1_override():
    response = client.get("/override1?level1=foo")
    assert response.json() == "foo"
    assert response.headers["content-type"] == "application/x-level-1"
    assert "x-level0" in response.headers
    assert "x-level1" in response.headers
    assert "x-level2" not in response.headers

    owner_ids: Optional[List[int]] = None

app = FastAPI()

@app.get("/items/invalidnone", response_model=Item)
def get_invalid_none():
    if flag:
        return {"name": "foo"}
    # if flag is False, at this point the function will implicitly return None
```