code: func (s *stateTracker) getState() (current folderState, changed time.Time, err error) {
  	s.mut.Lock()
  	current, changed, err = s.current, s.changed, s.err
  	s.mut.Unlock()
  	return
  }
docs: // getState returns the current state, the time when it last changed, and the
  // current error or nil.