Mac安装Python3报错Permission denied @ dir_s_mkdir - /usr/local/Frameworks

brew安装Python3时出现的问题：

Warning: python 3.6.4_4 is already installed, it's just not linked.
You can use `brew link python` to link this version.

发现/usr/local/下没有路径/usr/local/Frameworks
需要新建该路径，并修改权限
解决：

$ sudo mkdir /usr/local/Frameworks
$ sudo chown $(whoami):admin /usr/local/Frameworks

成功：

$ brew link python
Linking /usr/local/Cellar/python3/3.6.4... 1 symlinks created