code: func (tg *Group) UnmarshalYAML(unmarshal func(interface{}) error) error {
  	g := struct {
  		Targets []string       `yaml:"targets"`
  		Labels  model.LabelSet `yaml:"labels"`
  	}{}
  	if err := unmarshal(&g); err != nil {
  		return err
  	}
  	tg.Targets = make([]model.LabelSet, 0, len(g.Targets))
  	for _, t := range g.Targets {
  		tg.Targets = append(tg.Targets, model.LabelSet{
  			model.AddressLabel: model.LabelValue(t),
  		})
  	}
  	tg.Labels = g.Labels
  	return nil
  }
docs: // UnmarshalYAML implements the yaml.Unmarshaler interface.