brew 如何安装python3.6

Question

我有一台 mac，想安装 python 3.6 我试过：

$brew install --ignore-dependencies https://raw.githubusercontent.com/Homebrew/homebrew-core/f2a764ef944b1080be64bd88dca9a1d80130c558/Formula/python.rb 

但得到：

Error: Calling Installation of python from a GitHub commit URL is disabled! Use 'brew extract python' to stable tap on GitHub instead.

所以我试过：

$brew extract python https://raw.githubusercontent.com/Homebrew/homebrew-core/f2a764ef944b1080be64bd88dca9a1d80130c558/Formula/python.rb

但得到：

Error: Invalid tap name 'https://raw.githubusercontent.com/Homebrew/homebrew-core/f2a764ef944b1080be64bd88dca9a1d80130c558/Formula/python.rb'

我该怎么办？