code: func (r *GormTrackerRepository) List(ctx context.Context) ([]Tracker, error) {
  	defer goa.MeasureSince([]string{"goa", "db", "tracker", "query"}, time.Now())
  	var objs []Tracker
  	err := r.db.Find(&objs).Error
  	if err != nil && err != gorm.ErrRecordNotFound {
  		return nil, err
  	}
  	return objs, nil
  }
docs: // List returns tracker selected by the given criteria.Expression, starting with start (zero-based) and returning at most limit items