code: func (l SecondaryLayer) Finalize() {
  	l.lock.Lock()
  	e, err := l.store.SeekFirst()
  	if err != io.EOF {
  		_, v, err := e.Next()
  		for err != io.EOF {
  			if v != nil {
  				v.Finalize()
  			}
  			_, v, err = e.Next()
  		}
  		e.Close()
  	}
  	l.lock.Unlock()
  }
docs: // Finalize locks the layer and runs finalizers of all the keys
  // from this layer. Call this if you're going to drop an entire layer.