[fix] skip non-string result url/title/content

            self.paging = True

        for i, result in enumerate(results):

            if 'url' in result and not isinstance(result['url'], basestring):

                continue

            try:

                result['url'] = result['url'].decode('utf-8')

            except:

                pass

            if 'title' in result and not isinstance(result['title'], basestring):

                continue

            if 'content' in result and not isinstance(result['content'], basestring):

                continue

            position = i + 1

            self._merge_result(result, position)