code: func (gce *Cloud) CreateInstanceGroup(name string, zone string) (*compute.InstanceGroup, error) {
  	op, err := gce.service.InstanceGroups.Insert(
  		gce.projectID, zone, &compute.InstanceGroup{Name: name}).Do()
  	if err != nil {
  		return nil, err
  	}
  	if err = gce.waitForZoneOp(op, zone); err != nil {
  		return nil, err
  	}
  	return gce.GetInstanceGroup(name, zone)
  }
docs: // InstanceGroup Management
  // CreateInstanceGroup creates an instance group with the given instances. It is the callers responsibility to add named ports.