docs: def _check_markers(task_ids, offset=10):
      """Returns a flag for markers being found for the task_ids. If all task ids
      have markers True will be returned. Otherwise it will return False as soon
      as a None result is hit.
      """
  
      shuffle(task_ids)
      has_errors = False
  
      for index in xrange(0, len(task_ids), offset):
          keys = [ndb.Key(FuriousAsyncMarker, id)
                  for id in task_ids[index:index + offset]]
  
          markers = ndb.get_multi(keys)
  
          if not all(markers):
              logging.debug("Not all Async's complete")
              return False, None
  
          # Did any of the aync's fail? Check the success property on the
          # AsyncResult.
          has_errors = not all((marker.success for marker in markers))
  
      return True, has_errors