lastChild.previousSibling; // previousSibling because of line return \n
  testing.expectEqual('Comment', last_child.__proto__.constructor.name);
</script>

<script id=nextSibling>
  let next_sibling = link.nextSibling.nextSibling;
  testing.expectEqual('p', next_sibling.localName);
  testing.expectEqual('HTMLParagraphElement', next_sibling.__proto__.constructor.name);
  testing.expectEqual(null, $('#para-empty-child').nextSibling.nextSibling);
</script>

<script id=previousSibling>
  let prev_sibling = $('#