CI_Session::userdata PHP Method

    public function userdata($key = NULL)
    {
        if (isset($key)) {
            return isset($_SESSION[$key]) ? $_SESSION[$key] : NULL;
        } elseif (empty($_SESSION)) {
            return array();
        }
        $userdata = array();
        $_exclude = array_merge(array('__ci_vars'), $this->get_flash_keys(), $this->get_temp_keys());
        foreach (array_keys($_SESSION) as $key) {
            if (!in_array($key, $_exclude, TRUE)) {
                $userdata[$key] = $_SESSION[$key];
            }
        }
        return $userdata;
    }

 /**
  * {@inheritDoc}
  */
 public function get()
 {
     $value = $this->store->userdata($this->key);
     if ($value) {
         return unserialize($value);
     }
 }