code: func (s *Simulation) Services(name string) (services map[enode.ID]node.Service) {
  	nodes := s.Net.GetNodes()
  	services = make(map[enode.ID]node.Service)
  	for _, node := range nodes {
  		if !node.Up() {
  			continue
  		}
  		simNode, ok := node.Node.(*adapters.SimNode)
  		if !ok {
  			continue
  		}
  		services[node.ID()] = simNode.Service(name)
  	}
  	return services
  }
docs: // Services returns all services with a provided name
  // from nodes that are up.