code: public function insertBeforeSelf(SimpleXMLElement $new)
      {
          $tmp = dom_import_simplexml($this);
          $node = $tmp->ownerDocument->importNode(dom_import_simplexml($new), true);
  
          return simplexml_import_dom($this->insertNode($tmp, $node, 'before'), get_class($this));
      }
docs: Add a new sibling before this node
  
  This is a convenience method. The same result can be achieved with
  <code>
  $node->parentNode()->insertBefore($new, $node);
  </code>
  
  @param    SimpleXMLElement $new New node
  @return    SimpleDOM                    The inserted node