public function addURLs($urls)
  {
    //PHPCrawlerBenchmark::start("caching_urls");
    
    $cnt = count($urls);
    for ($x=0; $x<$cnt; $x++)
    {
      if ($urls[$x] != null)
      {
        $this->addURL($urls[$x]);
      }
    }
    
    //PHPCrawlerBenchmark::stop("caching_urls");
  }