mac上默認的python版本為2.7.10版本，需要升級到python3 版本，通過brew升級
- $brew install python3
提示錯誤
$ brew install python3 Warning: python3 3.6.3 is already installed, it's just not linked. You can use `brew link python3` to link this version. $ brew link python3 Linking /usr/local/Cellar/python3/3.6.3... Error: Permission denied @ dir_s_mkdir
發現/usr/local/下沒有路徑/usr/local/Frameworks
需要新建該路徑，並修改權限
解決：
$ sudo chown $(whoami):admin /usr/local/Frameworks
成功：
Linking /usr/local/Cellar/python3/3.6.3... 1 symlinks created