code: func (net *Network) Shutdown() {
  	for _, node := range net.Nodes {
  		log.Debug("Stopping node", "id", node.ID())
  		if err := node.Stop(); err != nil {
  			log.Warn("Can't stop node", "id", node.ID(), "err", err)
  		}
  		// If the node has the close method, call it.
  		if closer, ok := node.Node.(io.Closer); ok {
  			if err := closer.Close(); err != nil {
  				log.Warn("Can't close node", "id", node.ID(), "err", err)
  			}
  		}
  	}
  	close(net.quitc)
  }
docs: // Shutdown stops all nodes in the network and closes the quit channel