brew安裝Python3時(shí)出現(xiàn)的問題：
Warning: python 3.6.4_4 is already installed, it's just not linked.
You can use `brew link python` to link this version.
發(fā)現(xiàn)/usr/local/下沒有路徑/usr/local/Frameworks
需要新建該路徑释牺，并修改權(quán)限
解決：
$ 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
