code: func (m *model) GlobalSize(folder string) db.Counts {
  	m.fmut.RLock()
  	defer m.fmut.RUnlock()
  	if rf, ok := m.folderFiles[folder]; ok {
  		return rf.GlobalSize()
  	}
  	return db.Counts{}
  }
docs: // GlobalSize returns the number of files, deleted files and total bytes for all
  // files in the global model.