code: def reset_evaluators(self, evaluators):
          
          for obj_id, ev in self._tasks.copy().items():
              if ev not in evaluators:
                  del self._tasks[obj_id]
                  del self._objects[obj_id]
          ok = []
          for ev, obj_id in self._fetching:
              if ev in evaluators:
                  ok.append((ev, obj_id))
          self._fetching = ok
docs: Notify that some evaluators may be removed.