docs: def serialize_image(ctx, document, elem, root):
      """Serialize image element.
  
      This is not abstract enough.
      """
  
      _img = etree.SubElement(root, 'img')
      # make path configurable
  
      if elem.rid in document.relationships[ctx.options['relationship']]:
          img_src = document.relationships[ctx.options['relationship']][elem.rid].get('target', '')
          img_name, img_extension = os.path.splitext(img_src)
  
          _img.set('src', 'static/{}{}'.format(elem.rid, img_extension))
  
      fire_hooks(ctx, document, elem, _img, ctx.get_hook('img'))
  
      return root