code: func (s *nodeStore) Clean() {
  	s.mu.Lock()
  	for _, rn := range s.nodes {
  		rn.Heartbeat.Stop()
  	}
  	s.nodes = make(map[string]*registeredNode)
  	s.mu.Unlock()
  }
docs: // Clean removes all nodes and stops their heartbeats.
  // It's equivalent to invalidate all sessions.