code: public function insertXML($xml, $mode = 'append')
      {
          $tmp = dom_import_simplexml($this);
          $fragment = $tmp->ownerDocument->createDocumentFragment();
  
          /**
           * Disable error reporting
           */
          $use_errors = libxml_use_internal_errors(true);
  
          if (!$fragment->appendXML($xml)) {
              libxml_use_internal_errors($use_errors);
              throw new InvalidArgumentException(libxml_get_last_error()->message);
          }
          libxml_use_internal_errors($use_errors);
  
          $this->insertNode($tmp, $fragment, $mode);
  
          return $this;
      }
docs: Insert raw XML data
  
  @param    string $xml XML to insert
  @param    string $mode Where to add this tag: 'append' to current node,
  'before' current node or 'after' current node
  @throws BadMethodCallException
  @throws InvalidArgumentException
  @return    SimpleDOM            Current node