code: func NewChord(group *Group, callback *Signature) (*Chord, error) {
  	if callback.UUID == "" {
  		// Generate a UUID for the chord callback
  		callbackUUID := uuid.New().String()
  		callback.UUID = fmt.Sprintf("chord_%v", callbackUUID)
  	}
  
  	// Add a chord callback to all tasks
  	for _, signature := range group.Tasks {
  		signature.ChordCallback = callback
  	}
  
  	return &Chord{Group: group, Callback: callback}, nil
  }
docs: // NewChord creates a new chord (a group of tasks with a single callback
  // to be executed after all tasks in the group has completed)