1、使用pip安装包失败，报错：
Could not fetch URL https://pypi.python.org/simple/mitmproxy/: There was a problem confirming the ssl certificate: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645) - skipping
Could not find a version that satisfies the requirement mitmproxy (from versions: )
No matching distribution found for mitmproxy
可以通过国内镜像安装：pip install 包名-i http://pypi.douban.com/simple/ --trusted-host pypi.douban.com
--trusted-host pypi.douban.com 这是为了获得ssl证书的认证
2、使用pip安装包失败，报错 error: Microsoft Visual C++ 14.0 is required. Get it with "Microsoft Visual C++ Build Tools":
https://visualstudio.microsoft.com/downloads/
------需要安装
Microsoft Visual C++ Build Tools 2015
3、python3.7版本，pip版本太老，pip升级命令：
pip3 install --upgrade pip --trusted-host pypi.org --trusted-host files.pythonhosted.org
4、使用pip install XX出现错误consider using the '--user' option or check the permissions
纠正方法：pip install --user XX