code: func handlePing(s *rpcServer, cmd interface{}, closeChan <-chan struct{}) (interface{}, error) {
  	// Ask server to ping \o_
  	nonce, err := wire.RandomUint64()
  	if err != nil {
  		return nil, internalRPCError("Not sending ping - failed to "+
  			"generate nonce: "+err.Error(), "")
  	}
  	s.cfg.ConnMgr.BroadcastMessage(wire.NewMsgPing(nonce))
  
  	return nil, nil
  }
docs: // handlePing implements the ping command.