问题：
安装包出现Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by ‘ConnectTimeoutError
解决办法：
pip install selectivesearch -i http://pypi.douban.com/simple --trusted-host pypi.douban.com
原文：https://www.cnblogs.com/shenyexiaoqingxin/p/10443209.html