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
}
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
}
// UnmarshalYAML implements the yaml.Unmarshaler interface.