Windows
例如要安装 mysql-connector-python，注意 proxy 要用双引号括起来
pip install -i https://pypi.tuna.tsinghua.edu.cn/simple/ mysql-connector-python --proxy="http://serverIP:port"
Linux
例如要安装 mysql-connector-python
$ sudo pip install -i https://pypi.tuna.tsinghua.edu.cn/simple/ mysql-connector-python --proxy="http://serverIP:port"
