分享一些有用的python代码片，包含如下内容：
- Excel遍历密码自动化解密
- 带进度条下载文件
- 搜索给定目录下特定格式的文件，支持自定义查找深度
- 线程池的简单用法
Share some useful python snippets, Include the following content:
- Automatically decrypt password protected excel files.
- Download the file with the progress bar.
- Search specific format files from a given directory, support custom search depth.
- A demo about thread pool.