if user is None:
        raise credentials_exception
    return user


async def get_current_active_user(current_user: User = Depends(get_current_user)):
    if current_user.disabled:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user


@app.post("/token")
async def login_for_access_token(
    form_data: OAuth2PasswordRequestForm = Depends(),
) -> Token:

    if user is None:
        raise credentials_exception
    return user


async def get_current_active_user(
    current_user: Annotated[User, Depends(get_current_user)],
):
    if current_user.disabled:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user


@app.post("/token")
async def login_for_access_token(
    form_data: Annotated[OAuth2PasswordRequestForm, Depends()],

    )


@app.get(app.swagger_ui_oauth2_redirect_url, include_in_schema=False)
async def swagger_ui_redirect():
    return get_swagger_ui_oauth2_redirect_html()


@app.get("/redoc", include_in_schema=False)
async def redoc_html():
    return get_redoc_html(
        openapi_url=app.openapi_url,
        title=app.title + " - ReDoc",

        swagger_css_url="/static/swagger-ui.css",
    )


@app.get(app.swagger_ui_oauth2_redirect_url, include_in_schema=False)
async def swagger_ui_redirect():
    return get_swagger_ui_oauth2_redirect_html()


@app.get("/redoc", include_in_schema=False)
async def redoc_html():
    return get_redoc_html(
        openapi_url=app.openapi_url,
        title=app.title + " - ReDoc",

        @app.get("/items/{item_id}/")
        async def get_item(item_id: Annotated[int, Path(default=1)]):
            pass  # pragma: nocover

    with pytest.raises(
        AssertionError,
        match=(
            "`Query` default value cannot be set in `Annotated` for 'item_id'. Set the"
            " default value with `=` instead."
        ),
    ):

        @app.get("/")

from fastapi import Depends, FastAPI

app = FastAPI()


async def common_parameters(q: str | None = None, skip: int = 0, limit: int = 100):
    return {"q": q, "skip": skip, "limit": limit}


@app.get("/items/")
async def read_items(commons: dict = Depends(common_parameters)):
    return commons


@app.get("/users/")
async def read_users(commons: dict = Depends(common_parameters)):

router = APIRouter()


@router.get("/users/", tags=["users"])
async def read_users():
    return [{"username": "Rick"}, {"username": "Morty"}]


@router.get("/users/me", tags=["users"])
async def read_user_me():
    return {"username": "fakecurrentuser"}


@router.get("/users/{username}", tags=["users"])
async def read_user(username: str):

```Python
async with lifespan(app):
    await do_stuff()
```

When you create a context manager or an async context manager like above, what it does is that, before entering the `with` block, it will execute the code before the `yield`, and after exiting the `with` block, it will execute the code after the `yield`.

from fastapi import Depends


async def dependency_a():
    dep_a = generate_dep_a()
    try:
        yield dep_a
    finally:
        dep_a.close()


async def dependency_b(dep_a=Depends(dependency_a)):
    dep_b = generate_dep_b()
    try:
        yield dep_b
    finally:
        dep_b.close(dep_a)


async def dependency_c(dep_b=Depends(dependency_b)):
    dep_c = generate_dep_c()
    try:
        yield dep_c

    tags: Set[str] = set()


@app.post("/items/", response_model=Item, tags=["items"])
async def create_item(item: Item):
    return item


@app.get("/items/", tags=["items"])
async def read_items():
    return [{"name": "Foo", "price": 42}]


@app.get("/users/", tags=["users"])
async def read_users():