code: func (m *GracefulTerminationManager) GracefulDeleteRS(vs *utilipvs.VirtualServer, rs *utilipvs.RealServer) error {
  	// Try to delete rs before add it to graceful delete list
  	ele := &listItem{
  		VirtualServer: vs,
  		RealServer:    rs,
  	}
  	deleted, err := m.deleteRsFunc(ele)
  	if err != nil {
  		klog.Errorf("Delete rs %q err: %v", ele.String(), err)
  	}
  	if deleted {
  		return nil
  	}
  	rs.Weight = 0
  	err = m.ipvs.UpdateRealServer(vs, rs)
  	if err != nil {
  		return err
  	}
  	klog.V(5).Infof("Adding an element to graceful delete rsList: %+v", ele)
  	m.rsList.add(ele)
  	return nil
  }
docs: // GracefulDeleteRS to update rs weight to 0, and add rs to graceful terminate list