public function save()
    {   
        $result = null; 
        $i = 0;
        foreach (
            $iterator = new RecursiveIteratorIterator(
                new RecursiveDirectoryIterator(
                    $this->_dir, 
                    RecursiveDirectoryIterator::SKIP_DOTS
                ),
                RecursiveIteratorIterator::SELF_FIRST
            ) as $item
        ) {
            if (!$item->isDir()) { 
                $filename = $this->_dir . 
                            DIRECTORY_SEPARATOR . 
                            $iterator->getSubPathName(); 
                $_tweet = file_get_contents($filename); 
                $tweet = json_decode($_tweet, TRUE);  
                $params = ['index' => $this->_esindex,
                            'type' => $this->_estype,
                            'body' => $tweet];
                $result = $this->_es->index($params); 
                $i++;
            }
        }
        return $i;
    }