## The symptom

Importing `Secret` and `Verifier` from `paddle_billing.Notifications` to verify
webhooks failed on version 0.3.0 with:

```
ModuleNotFoundError: No module named 'paddle_billing.Resources.IPAddresses'
```

The 0.3.0 release shipped with a broken internal import. The import chain broke
at `Client.py`, so any import of the package failed, not just the Notifications
import.

## The fix

```
pip install -U 'paddle-billing>=0.3.1'
```

Fixed in 0.3.1; the reporter confirmed the fix within hours of the 0.3.1
release.

## The general lesson

When every import of a package fails on a fresh release (not just one
submodule), suspect a broken release artifact, not your code. Check the
project's issues for the release version before restructuring your imports.