CI_Session::keep_flashdata PHP Method

    public function keep_flashdata($key)
    {
        $this->mark_as_flash($key);
    }

 public function keep_flashdata($key = null)
 {
     if ($key !== null) {
         parent::keep_flashdata($key);
     } else {
         // An added feature: Keep all the flash data.
         parent::keep_flashdata($this->get_flash_keys());
     }
 }