public function set($token, $type)
    {
        if ($type != 'request_token' && $type != 'access_token') {
            throw new \Dropbox\Exception("Expected a type of either 'request_token' or 'access_token', got '$type'");
        } else {
            $token = $this->encrypt($token);
            $_SESSION[$this->namespace][$this->userID][$type] = $token;
        }
    }