code: func (s *ChainService) PeerByAddr(addr string) *ServerPeer {
  	for _, peer := range s.Peers() {
  		if peer.Addr() == addr {
  			return peer
  		}
  	}
  	return nil
  }
docs: // PeerByAddr lets the caller look up a peer address in the service's peer
  // table, if connected to that peer address.