code: func (w *wrapper) Folders() map[string]FolderConfiguration {
  	w.mut.Lock()
  	defer w.mut.Unlock()
  	if w.folderMap == nil {
  		w.folderMap = make(map[string]FolderConfiguration, len(w.cfg.Folders))
  		for _, fld := range w.cfg.Folders {
  			w.folderMap[fld.ID] = fld.Copy()
  		}
  	}
  	return w.folderMap
  }
docs: // Folders returns a map of folders. Folder structures should not be changed,
  // other than for the purpose of updating via SetFolder().