code: def refresh_urls_and_dirs(self, urls, dirs):
          
          req = {}
          if urls is not None and len(urls) > 0:
              req.update({"urls": urls})
          if dirs is not None and len(dirs) > 0:
              req.update({"dirs": dirs})
  
          body = json.dumps(req)
          url = '{0}/v2/tune/refresh'.format(self.server)
          return self.__post(url, body)
docs: 刷新文件目录，文档 http://developer.qiniu.com/article/fusion/api/refresh.html
  
          Args:
             urls: 待刷新的目录列表
             dirs: 待刷新的文件列表
  
          Returns:
             一个dict变量和一个ResponseInfo对象
             参考代码 examples/cdn_manager.py