"title": "Price",
                            "exclusiveMinimum": 0.0,
                            "type": "number",
                            "description": "The price must be greater than zero",
                        },
                        "tax": IsDict(
                            {
                                "title": "Tax",

                            "title": "Price",
                            "exclusiveMinimum": 0.0,
                            "type": "number",
                            "description": "The price must be greater than zero",
                        },
                        "tax": IsDict(
                            {
                                "title": "Tax",

Number validations also work for `float` values.

Here's where it becomes important to be able to declare <abbr title="greater than"><code>gt</code></abbr> and not just <abbr title="greater than or equal"><code>ge</code></abbr>. As with it you can require, for example, that a value must be greater than `0`, even if it is less than `1`.

So, `0.5` would be a valid value. But `0.0` or `0` would not.

This example doesn't implement the callback itself (that could be just a line of code), only the documentation part.

!!! tip
    The actual callback is just an HTTP request.

![ReDoc](https://fastapi.tiangolo.com/img/index/index-06-redoc-02.png)

### Just Modern Python

It's all based on standard **Python type** declarations (thanks to Pydantic). No new syntax to learn. Just standard modern Python.

!!! info
    The `app.webhooks` object is actually just an `APIRouter`, the same type you would use when structuring your app with multiple files.

        Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="8-9"
    {!> ../../../docs_src/dependencies/tutorial005.py!}
    ```

It declares an optional query parameter `q` as a `str`, and then it just returns it.

This is quite simple (not very useful), but will help us focus on how the sub-dependencies work.

## Second dependency, "dependable" and "dependant"

    You could also use `from starlette import status`.

    **FastAPI** provides the same `starlette.status` as `fastapi.status` just as a convenience for you, the developer. But it comes directly from Starlette.

## Tags

You can add tags to your *path operation*, pass the parameter `tags` with a `list` of `str` (commonly just one `str`):

=== "Python 3.10+"

    ```Python hl_lines="15  20  25"

When you declare a default value for non-path parameters (for now, we have only seen query parameters), then it is not required.

If you don't want to add a specific value but just make it optional, set the default as `None`.

But when you want to make a query parameter required, you can just not declare any default value:

```Python hl_lines="6-7"
{!../../../docs_src/query_params/tutorial005.py!}
```

    )
    assert response.status_code == 200, response.text
    assert response.json() == {"msg": "Invoice received"}


def test_dummy_callback():
    # Just for coverage
    invoice_notification({})


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