{!../../../docs_src/python_types/tutorial002.py!}
```

That is not the same as declaring default values like would be with:

```Python
    first_name="john", last_name="doe"
```

It's a different thing.

We are using colons (`:`), not equals (`=`).

And adding type hints normally doesn't change what happens from what would happen without them.

  optional k8s.io.apimachinery.pkg.apis.meta.v1.ListMeta metadata = 1;

  // items is a list of schema objects.
  repeated Event items = 2;
}

// EventSeries contain information on series of events, i.e. thing that was/is happening
// continuously for some time.
message EventSeries {
  // count is the number of occurrences in this series up to the last heartbeat time.
  optional int32 count = 1;

    To learn more about the `Request` check <a href="https://www.starlette.io/requests/" class="external-link" target="_blank">Starlette's docs about Requests</a>.

The only thing the function returned by `GzipRequest.get_route_handler` does differently is convert the `Request` to a `GzipRequest`.

!!! tip
    The `shutdown` would happen when you are **stopping** the application.

    Maybe you need to start a new version, or you just got tired of running it. 🤷

### Lifespan function

The first thing to notice, is that we are defining an async function with `yield`. This is very similar to Dependencies with `yield`.

```Python hl_lines="14-19"
{!../../../docs_src/events/tutorial003.py!}
```

	// (e.g. LoadBalanced Service packets, etc) that need to be authenticated/captured/proxied.
	//
	// We want to do the same thing in ambient but can't rely on podSpec injection. So, do effectively the same thing,
	// but with iptables rules - use `--socket-exists` as a proxy for "is this a forwarded packet" vs "is this originating from

```

!!! tip
    The `callback_url` query parameter uses a Pydantic <a href="https://docs.pydantic.dev/latest/concepts/types/#urls" class="external-link" target="_blank">URL</a> type.

The only new thing is the `callbacks=invoices_callback_router.routes` as an argument to the *path operation decorator*. We'll see what that is next.

## Documenting the callback

The actual callback code will depend heavily on your own API app.

Let's go a little deeper into the details.

FastAPI uses a standard for building Python web frameworks and servers called <abbr title="Asynchronous Server Gateway Interface">ASGI</abbr>. FastAPI is an ASGI web framework.

The main thing you need to run a **FastAPI** application (or any other ASGI application) in a remote server machine is an ASGI server program like **Uvicorn**, this is the one that comes by default in the `fastapi` command.

    if ((!features.contains(IteratorFeature.SUPPORTS_REMOVE) && removes > 1)
        || (stimuli.length >= 5 && removes > 2)) {
      // removes are the most expensive thing to test, since they often throw exceptions with stack
      // traces, so we test them a bit less aggressively
      return;
    }

In contrast to a "**container image**" that is the stored static contents, a "**container**" normally refers to the running instance, the thing that is being **executed**.

ambient mode, the CNI plugin is effectively just a shim to catch pod creation events and notify the CNI agent early enough to set up network redirection before the pod is fully started. This is necessary because the CNI plugin is effectively the first thing to see a scheduled pod - before the K8S control plane will see things like the pod IP or networking info, the CNI will - but the CNI plugin alone is not sufficient to handle all pod events (already-started pod updates, rebuilding current state on CNI...