code: func (c Client) CleanupOld(age int) error {
  	conn := c.Pool.Get()
  	defer conn.Close()
  
  	currentTime := db.MakeTimestamp()
  	end := currentTime - int64(age)
  	objects, err := getObjectsByScore(conn, db.Notification+":created", 0, end, -1)
  	if err != nil {
  		return err
  	}
  
  	notifications, err := unmarshalNotifications(objects)
  	if err != nil {
  		return err
  	}
  
  	for _, notification := range notifications {
  		err = c.DeleteNotificationById(notification.ID)
  		if err != nil {
  			return err
  		}
  		transmissions, err := c.GetTransmissionsByNotificationSlug(notification.Slug, -1)
  		if err != nil {
  			return err
  		}
  		for _, transmission := range transmissions {
  			err = deleteTransmission(conn, transmission.ID)
  			if err != nil {
  				return err
  			}
  		}
  	}
  
  	return nil
  }
docs: // Cleanup delete old notifications and associated transmissions