old_contents: from .version import __version__
  from .tasks import SyncEntitiesTask
  from .models import EntityModelMixin, Entity, BaseEntityModel, EntityModelManager
  from .sync import sync_entities, turn_on_syncing, turn_off_syncing
  
new_contents: from .version import __version__
  from .tasks import SyncEntitiesTask
  from .models import EntityModelMixin, Entity, BaseEntityModel, EntityModelManager, EntityRelationship
  from .sync import sync_entities, turn_on_syncing, turn_off_syncing
  
subject: Update __init__.py