docs: def delete_orphan_translations(condition=None):
  		"""
  		Delete orphan translations.
  		This method needs refactoring to be improve its performance.
  		"""
  		if condition is None:
  			condition = {}
  		# TODO: optimize using one SQL sentence
  		translations = FieldTranslation.objects.all()
  		for translation in translations:
  			translation._load_source_model()
  			condition["id"] = translation.object_id
  			if not translation.source_model.objects.filter(**condition).exists():
  				translation.delete()