function crawlerDetect($USER_AGENT = '') {
    $crawlers = array('Googlebot', 'Bingbot', 'Slurp', 'DuckDuckBot', 'Baiduspider', 'YandexBot', 'facebot', 'ia_archiver');
    foreach ($crawlers as $crawler) {
      if (stripos($USER_AGENT, $crawler) !== false) {
        return true;
      }
    }
    return false;
  }
<br />
<b>Warning</b>:  session_start(): Cannot send session cache limiter - headers already sent (output started at /home/kmawbbcz/avn.com.vn/includes/class_libs.php:874) in <b>/home/kmawbbcz/avn.com.vn/libraries/vntrust/session/session.php</b> on line <b>407</b><br />
<br />
<b>Warning</b>:  Cannot modify header information - headers already sent by (output started at /home/kmawbbcz/avn.com.vn/includes/class_libs.php:874) in <b>/home/kmawbbcz/avn.com.vn/libraries/vntrust/session/session.php</b> on line <b>410</b><br />
<br />
<b>Fatal error</b>:  Call to undefined method Lib::crawlerDetect() in <b>/home/kmawbbcz/avn.com.vn/index.php</b> on line <b>37</b><br />