Previous versions used homebrew to install the various versions. As suggested in the comments, it's better to use pyenv instead. If you are looking for the previous version of this document, see the revision history.
$ brew update
$ brew install pyenv
$ pyenv install 3.5.0
$ pyenv install 3.4.3
$ pyenv install 3.3.6
$ pyenv install 3.2.6
$ pyenv install 2.7.10
$ pyenv install 2.6.9