para-empty').previousSibling.previousSibling;
  testing.expectEqual('a', prev_sibling.localName);
  testing.expectEqual('HTMLAnchorElement', prev_sibling.__proto__.constructor.name);
  testing.expectEqual(null, content.previousSibling);
</script>

<script id=parentElement>
  let parent = $('#para').parentElement;
  testing.expectEqual('div', parent.localName);
  testing.expectEqual('HTMLDivElement', parent.__proto__.constructor.name)

  let h = content.parentElement.parentElement;
  testing.expectEqual(null