It checks for a form token in the request. This function is used in conjunction with \JHtml::_('form.token') or \JSession::getFormToken.

• string $method - The request method in which to look for the token key.
• boolean $redirect - Whether to implicitly redirect user to the referrer page on failure or simply return false.
• return boolean - True if found and valid, otherwise return false or redirect to referrer page.

public function checkToken($method = 'post', $redirect = true)
 {
 $valid = \JSession::checkToken($method);

if (!$valid && $redirect)
 {
 $referrer = $this->input->server->getString('HTTP_REFERER');

if (!\JUri::isInternal($referrer))
 {
 $referrer = 'index.php';
 }

$app = \JFactory::getApplication();
 $app->enqueueMessage(\JText::_('JINVALID_TOKEN_NOTICE'), 'warning');
 $app->redirect($referrer);
 }

return $valid;
 }