public function getLists($listType = 2, $isPrivate = true, $folder = null) {
        $data["Envelope"] = array(
            "Body" => array(
                "GetLists" => array(
                    "VISIBILITY" => ($isPrivate ? '0' : '1'),
                    "FOLDER_ID" => $folder,
                    "LIST_TYPE" => $listType,
                ),
            ),
        );
        $response = $this->_request($data);
        $result = $response["Envelope"]["Body"]["RESULT"];
        if ($this->_isSuccess($result)) {
            if (isset($result['LIST']))
                return $result['LIST'];
            else {
                return array(); //?
            }
        } else {
            throw new \Exception("GetLists Error: ".$this->_getErrorFromResponse($response));
        }
    }