code: func (s *Store) RemovePeer(peer string) error {
  	err := s.raft.RemovePeer(peer).Error()
  	if err == raft.ErrNotLeader {
  		err = ErrNotLeader
  	} else if err == raft.ErrUnknownPeer {
  		return nil
  	}
  	return err
  }
docs: // RemovePeer removes a peer from the raft cluster. Panic if store is not open yet.