docs: def _cleanup_markers(context_id, task_ids):
      """Delete the FuriousAsyncMarker entities corresponding to ids."""
  
      logging.debug("Cleanup %d markers for Context %s",
                    len(task_ids), context_id)
  
      # TODO: Handle exceptions and retries here.
      delete_entities = [ndb.Key(FuriousAsyncMarker, id) for id in task_ids]
      delete_entities.append(ndb.Key(FuriousCompletionMarker, context_id))
  
      ndb.delete_multi(delete_entities)
  
      logging.debug("Markers cleaned.")