code: def complete_event(self, event_id: str):
          
          event_ids = DB.get_list(self._processed_key)
          if event_id not in event_ids:
              raise KeyError('Unable to complete event. Event {} has not been '
                             'processed (ie. it is not in the processed '
                             'list).'.format(event_id))
          DB.remove_from_list(self._processed_key, event_id, pipeline=True)
          key = _keys.completed_events(self._object_type, self._subscriber)
          DB.append_to_list(key, event_id, pipeline=True)
          DB.execute()
docs: Complete the specified event.