code: private Renderer recycle(View convertView, T content) {
      Renderer renderer = (Renderer) convertView.getTag();
      renderer.onRecycle(content);
      return renderer;
    }
docs: Recycles the Renderer getting it from the tag associated to the renderer root view. This view
  is not used with RecyclerView widget.
  
  @param convertView that contains the tag.
  @param content to be updated in the recycled renderer.
  @return a recycled renderer.