[SSL: CERTIFICATE_VERIFY_FAILED]

        在anaconda环境下使用pip安装包时，有以下错误：

           Cache entry deserialization failed, entry ignored
  Could not fetch URL https://pypi.tuna.tsinghua.edu.cn/simple/tensorflow/: There was a problem confirming the ssl certificate: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:748) - skipping
  Could not find a version that satisfies the requirement tensorflow==1.4.0 (from versions: )
No matching distribution found for tensorflow==1.4.0

        发现是对源网站的证书不信任，所以在pip的过程中加入信任网站即可，如下：

        pip install tensorflow==1.4.0 --trusted-host pypi.tuna.tsinghua.edu.cn