code: func (g *Cloud) AggregatedListNetworkEndpointGroup() (map[string][]*computebeta.NetworkEndpointGroup, error) {
  	ctx, cancel := cloud.ContextWithCallTimeout()
  	defer cancel()
  
  	mc := newNetworkEndpointGroupMetricContext("aggregated_list", "")
  	// TODO: filter for the region the cluster is in.
  	all, err := g.c.BetaNetworkEndpointGroups().AggregatedList(ctx, filter.None)
  	if err != nil {
  		return nil, mc.Observe(err)
  	}
  	ret := map[string][]*computebeta.NetworkEndpointGroup{}
  	for key, byZone := range all {
  		// key is "zones/<zone name>"
  		parts := strings.Split(key, "/")
  		if len(parts) != 2 {
  			return nil, mc.Observe(fmt.Errorf("invalid key for AggregatedListNetworkEndpointGroup: %q", key))
  		}
  		zone := parts[1]
  		ret[zone] = append(ret[zone], byZone...)
  	}
  	return ret, mc.Observe(nil)
  }
docs: // AggregatedListNetworkEndpointGroup returns a map of zone -> endpoint group.