public function closeRequest()
 {
     $handle = @fopen($this->batches_file, "r");
     if ($handle) {
         file_put_contents($this->request_file, Obj2xml::generateRequestHeader($this->config, $this->num_batch_requests), FILE_APPEND);
         while (($buffer = fgets($handle, 4096)) !== false) {
             file_put_contents($this->request_file, $buffer, FILE_APPEND);
         }
         if (!feof($handle)) {
             throw new \RuntimeException("Error when reading batches file at {$this->batches_file}. Please check your privilege.");
         }
         fclose($handle);
         file_put_contents($this->request_file, "</litleRequest>", FILE_APPEND);
         unlink($this->batches_file);
         unset($this->batches_file);
         $this->closed = true;
     } else {
         throw new \RuntimeException("Could not open batches file at {$this->batches_file}. Please check your privilege.");
     }
 }