code: func (n *Node) NodeRemoved() {
  	n.removeRaftOnce.Do(func() {
  		atomic.StoreUint32(&n.isMember, 0)
  		close(n.RemovedFromRaft)
  	})
  }
docs: // NodeRemoved signals that node was removed from cluster and should stop.
  // Part of transport.Raft interface.