code: func (s *Services) WithLabel(label string) ([]Service, error) {
  	for l, services := range *s {
  		if strings.EqualFold(label, l) {
  			return services, nil
  		}
  	}
  
  	return nil, fmt.Errorf("no services with label %s", label)
  }
docs: // WithLabel finds the service with the specified label.