code: public function setFlash($key, $value, $redirect = null)
      {
          $this->set('_nur_flash', [$key => $value]);
  
          if (! is_null($redirect)) {
              uri()->redirect($redirect);
          }
  
          return false;
      }
docs: Setting Flash Message
  
  @param string $key
  @param mixed $value
  @param string $redirect
  
  @return bool