pip install datetime
pip install datetime -i https://pypi.tuna.tsinghua.edu.cn/simple
pip install -i https://pypi.tuna.tsinghua.edu.cn/simple datetime
清华大学:https://pypi.tuna.tsinghua.edu.cn/simple
豆瓣:https://pypi.douban.com/simple
阿里云:https://mirrors.aliyun.com/pypi/simple
中国科技大学:https://pypi.mirrors.ustc.edu.cn/simpl