code: func (g *Cloud) CreateInstanceGroup(ig *compute.InstanceGroup, zone string) error {
  	ctx, cancel := cloud.ContextWithCallTimeout()
  	defer cancel()
  
  	mc := newInstanceGroupMetricContext("create", zone)
  	return mc.Observe(g.c.InstanceGroups().Insert(ctx, meta.ZonalKey(ig.Name, zone), ig))
  }
docs: // CreateInstanceGroup creates an instance group with the given
  // instances. It is the callers responsibility to add named ports.