SessionHandlerInterface::close PHP Method

    public function close();

 /**
  * {@inheritdoc}
  */
 public function close()
 {
     $trace = \Drupal::service('session_test.session_handler_proxy_trace');
     $trace[] = ['BEGIN', $this->optionalArgument, __FUNCTION__];
     $result = $this->sessionHandler->close();
     $trace[] = ['END', $this->optionalArgument, __FUNCTION__];
     return $result;
 }