code: func (m *model) CurrentSequence(folder string) (int64, bool) {
  	m.fmut.RLock()
  	fs, ok := m.folderFiles[folder]
  	m.fmut.RUnlock()
  	if !ok {
  		// The folder might not exist, since this can be called with a user
  		// specified folder name from the REST interface.
  		return 0, false
  	}
  
  	return fs.Sequence(protocol.LocalDeviceID), true
  }
docs: // CurrentSequence returns the change version for the given folder.
  // This is guaranteed to increment if the contents of the local folder has
  // changed.