code: func (ts *Store) IsRendered(id string) (bool, error) {
  	// if the "rendered" flag file exists, assume that the store is already
  	// fully rendered.
  	treepath := ts.GetPath(id)
  	_, err := os.Stat(filepath.Join(treepath, renderedfilename))
  	if os.IsNotExist(err) {
  		return false, nil
  	}
  	if err != nil {
  		return false, err
  	}
  	return true, nil
  }
docs: // IsRendered checks if the tree store with the provided id is fully rendered