code: func (b *Backend) GroupTaskStates(groupUUID string, groupTaskCount int) ([]*tasks.TaskState, error) {
  	groupMeta, err := b.getGroupMeta(groupUUID)
  	if err != nil {
  		return nil, err
  	}
  
  	return b.getStates(groupMeta.TaskUUIDs...)
  }
docs: // GroupTaskStates ...