pip安装第三方包PIL失败

 安装报错信息如下：

ERROR: Could not find a version that satisfies the requirement PIL (from versions: none)
ERROR: No matching distribution found for PIL

 解决方式：

pip install PIL-i https://pypi.tuna.tsinghua.edu.cn/simple/

pip install 包名-i http://pypi.douban.com/simple/ --trusted-host pypi.douban.com