code: public function isValidCSRF($token, $action = null)
      {
          if (!$this->csrf->checkToken($token, $action)) {
              $this->logger->warning(
                  "CSRFt mismatch: for {action} from {addr}",
                  array(
                      "action" => $action,
                      "addr" => $_SERVER['REMOTE_ADDR']
                  )
              );
              $this->session->addFlash("error", "Invalid CSRF token, please try again.");
              return false;
          } else {
              return true;
          }
      }
docs: {@inheritdoc}