code: public function count($siteId, $language)
      {
          $qa = $this->createAggregationQueryBuilderWithSiteIdAndLanguage($siteId, $language);
          $qa->match(array('deleted' => false));
          $elementName = 'node';
          $qa->sort(array('createdAt' => 1));
          $qa->group(array(
              '_id' => array('nodeId' => '$nodeId'),
              $elementName => array('$last' => '$$ROOT')
          ));
  
          return $this->countDocumentAggregateQuery($qa);
      }
docs: @param string  $siteId
  @param string  $language
  
  @return int