Как получить данные из сессии без session_start()?

/**
 * Wraps around $_SESSION
 *
 * @param string $name name of session variable to set
 * @param mixed $value value for the variable. Set this to null to unset the variable from the session.
 *
 * @return mixed value for the session variable
 */
function session($name, $value = null) {

    static $session_active = false;

    if ($session_active === false) {

        if (($current = ini_get('session.use_trans_sid')) === false)
            exit('Calls to session() requires [session.use_trans_sid] to be set');

        $test = "mix{$current}{$current}";

        $prev = @ini_set('session.use_trans_sid', $test);
        $peek = @ini_set('session.use_trans_sid', $current);

        if ($peek !== $current && $peek !== false)
            session_start();

        $session_active = true;
    }

    if (func_num_args() === 1)
        return (isset($_SESSION[$name]) ? $_SESSION[$name] : null);

    if ($value === null)
        unset($_SESSION[$name]);
    else
        $_SESSION[$name] = $value;
}