code: func (g *Cloud) AttachNetworkEndpoints(name, zone string, endpoints []*computebeta.NetworkEndpoint) error {
  	ctx, cancel := cloud.ContextWithCallTimeout()
  	defer cancel()
  
  	mc := newNetworkEndpointGroupMetricContext("attach", zone)
  	req := &computebeta.NetworkEndpointGroupsAttachEndpointsRequest{
  		NetworkEndpoints: endpoints,
  	}
  	return mc.Observe(g.c.BetaNetworkEndpointGroups().AttachNetworkEndpoints(ctx, meta.ZonalKey(name, zone), req))
  }
docs: // AttachNetworkEndpoints associates the referenced endpoints with the named endpoint group in the zone