def _process_response(self, response, marker_elems=None):
        """
        Helper to process the xml response from AWS
        """
        body = response.read()
        #print body
        if '<Errors>' not in body:
            rs = ResultSet(marker_elems)
            h = handler.XmlHandler(rs, self)
            xml.sax.parseString(body, h)
            return rs
        else:
            raise MTurkRequestError(response.status, response.reason, body)