My intention was to pull that if statement into the handler, so instead of:

```python
    pdu_data = dr.inspect_delivery_report(pdu)
    if pdu_data is not None:
        yield dr.handle_delivery_report_pdu(pdu_data)
        return
```

one does:

```python
    handled = yield dr.handle_pdu(pdu)
    if handled:
        return
```