code: func (g *Cloud) SetNamedPortsOfInstanceGroup(igName, zone string, namedPorts []*compute.NamedPort) error {
  	ctx, cancel := cloud.ContextWithCallTimeout()
  	defer cancel()
  
  	mc := newInstanceGroupMetricContext("set_namedports", zone)
  	req := &compute.InstanceGroupsSetNamedPortsRequest{NamedPorts: namedPorts}
  	return mc.Observe(g.c.InstanceGroups().SetNamedPorts(ctx, meta.ZonalKey(igName, zone), req))
  }
docs: // SetNamedPortsOfInstanceGroup sets the list of named ports on a given instance group