问题描述：
当在命令窗口（服务器中的conda环境下）用pip install imgaug指令 想下载第三方库的时候，一直失败。
报错信息：
WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.tuna.tsinghua.edu.cn', port=443): Read timed out. (read timeout=15)")': /simple/imgaug/
WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.tuna.tsinghua.edu.cn', port=443): Read timed out. (read timeout=15)")': /simple/imgaug/
WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.tuna.tsinghua.edu.cn', port=443): Read timed out. (read timeout=15)")': /simple/imgaug/
WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.tuna.tsinghua.edu.cn', port=443): Read timed out. (read timeout=15)")': /simple/imgaug/
WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.tuna.tsinghua.edu.cn', port=443): Read timed out. (read timeout=15)")': /simple/imgaug/
ERROR: Could not find a version that satisfies the requirement imgaug (from versions: none)
ERROR: No matching distribution found for imgaug
解决方法：
方法一：换源。
如果想使用清华大学的 PyPI 镜像源来安装 imgaug 包，可以在 pip 命令中添加 -i 选项并指定清华大学 PyPI 镜像源的 URL。例如：
pip install -i https://pypi.tuna.tsinghua.edu.cn/simple imgaug其他备用源如下所示：
阿里云源 https://mirrors.aliyun.com/pypi/simple/
豆瓣源 https://pypi.douban.com/simple/
清华源 https://pypi.tuna.tsinghua.edu.cn/simple/
中科大源 https://pypi.mirrors.ustc.edu.cn/simple/
方法二 ：信任源
改用豆瓣源镜像，并加上信任动作
pip install 库名 -i http://pypi.douban.com/simple --trusted-host pypi.douban.com
改用清华源镜像，并加上信任动作
pip install 库名 -i https://pypi.tuna.tsinghua.edu.cn/simple pip --trusted-host pypi.tuna.tsinghua.edu.cn方法三：更新pip
pip版本低，cmd一直提示你提升版本，查询了百度上面很多方法，给出了一条命令语句
pip install --upgrade pip方法四：检查网络
检查是否有科学上网，若有，则关闭科学上网即可。