def dependency_list() -> List[str]:
    return []


DepList = Annotated[List[str], Depends(dependency_list)]


def create_dependency(name: str):
    def fun(deps: DepList):
        deps.append(name)

    return Depends(fun)


router = APIRouter(dependencies=[create_dependency("router")])
prefix_router = APIRouter(dependencies=[create_dependency("prefix_router")])

That demonstrates how the Proxy (Traefik) uses the path prefix and how the server (Uvicorn) uses the `root_path` from the option `--root-path`.

### Check the docs UI

But here's the fun part. ✨

---

"_I’m over the moon excited about **FastAPI**. It’s so fun!_"

---

"_I’m over the moon excited about **FastAPI**. It’s so fun!_"

---

"_I’m over the moon excited about **FastAPI**. It’s so fun!_"

---

"_I’m over the moon excited about **FastAPI**. It’s so fun!_"

    assert response.status_code == 200
    assert response.json() == {
        "name": "Island In The Moon",
        "price": 12.99,
        "description": "A place to be be playin' and havin' fun",
        "tags": ["breater"],
        "tax": None,
    }


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

        {
            "name": "Breaters",
            "items": [
                {
                    "name": "Island In The Moon",
                    "description": "A place to be be playin' and havin' fun",
                },
                {"name": "Holy Buddies", "description": None},
            ],
        },
        {
            "name": "System of an Up",
            "items": [
                {

    ```Python
    q: Annotated[Union[str, None]] = None
    ```

Both of those versions mean the same thing, `q` is a parameter that can be a `str` or `None`, and by default, it is `None`.

Now let's jump to the fun stuff. 🎉

## Add `Query` to `Annotated` in the `q` parameter

Now that we have this `Annotated` where we can put more metadata, add `Query` to it, and set the parameter `max_length` to 50:

=== "Python 3.10+"

---

"_I’m over the moon excited about **FastAPI**. It’s so fun!_"