public function listOrders($request)
    {
        if (!($request instanceof MarketplaceWebServiceOrders_Model_ListOrdersRequest)) {
            $request = new MarketplaceWebServiceOrders_Model_ListOrdersRequest($request);
        }
        $parameters = $request->toQueryParameterArray();
        $parameters['Action'] = 'ListOrders';
        $httpResponse = $this->_invoke($parameters);

        $response = MarketplaceWebServiceOrders_Model_ListOrdersResponse::fromXML($httpResponse['ResponseBody']);
        $response->setResponseHeaderMetadata($httpResponse['ResponseHeaderMetadata']);
        return $response;
    }