code: func (iter *FileIter) ForEach(cb func(*File) error) error {
  	defer iter.Close()
  
  	for {
  		f, err := iter.Next()
  		if err != nil {
  			if err == io.EOF {
  				return nil
  			}
  
  			return err
  		}
  
  		if err := cb(f); err != nil {
  			if err == storer.ErrStop {
  				return nil
  			}
  
  			return err
  		}
  	}
  }
docs: // ForEach call the cb function for each file contained in this iter until
  // an error happens or the end of the iter is reached. If plumbing.ErrStop is sent
  // the iteration is stop but no error is returned. The iterator is closed.