code: func (n *Network) OrdererGroupRunner() ifrit.Runner {
  	members := grouper.Members{}
  	for _, o := range n.Orderers {
  		members = append(members, grouper.Member{Name: o.ID(), Runner: n.OrdererRunner(o)})
  	}
  	return grouper.NewParallel(syscall.SIGTERM, members)
  }
docs: // OrdererGroupRunner returns a runner that can be used to start and stop all
  // orderers in a network.