def METHOD_NAME(self, related_instance):
    """If related_models is set, define how to retrieve the Car instance(s) from the related model.
    The related_models option should be used with caution because it can lead in the index
    to the updating of a lot of items.
    """
    if isinstance(related_instance, IastAgent):
        if related_instance.bind_project_id < 0:
            return Asset.objects.filter(agent_id=related_instance.pk).all()
        return None
    return None