Thought about it: short-circuiting and using event return values will currently not be supported.

You can achieve that manually:

```php
$cachingListener = function (ExtractEvent $event) use ($someCache) {
    if ($cache->knows($event->getExtractionObject()) {
        $event->setExtractedData($cache->get($event->getExtractionObject()));
        
        return false; // or explicitly stop propagation
    }
}
```

So I won't change the implementation for now. Short-circuiting may be supported later on