code: func (f *sendReceiveFolder) checkToBeDeleted(cur protocol.FileInfo, scanChan chan<- string) error {
  	stat, err := f.fs.Lstat(cur.Name)
  	if err != nil {
  		if fs.IsNotExist(err) {
  			// File doesn't exist to start with.
  			return nil
  		}
  		// We can't check whether the file changed as compared to the db,
  		// do not delete.
  		return err
  	}
  	changed, err := f.itemChanged(stat, cur, true, scanChan)
  	if err != nil {
  		return err
  	}
  	if changed {
  		return errModified
  	}
  	return nil
  }
docs: // checkToBeDeleted makes sure the file on disk is compatible with what there is
  // in the DB before the caller proceeds with actually deleting it.
  // I.e. non-nil error status means "Do not delete!".