pyenv
Simple Python version management
pyenv is a tool for the simple management of Python versions: it lets you easily switch between different Python versions, offering support for per-project Python versions. pyenv is an uncomplicated, unobtrusive tool that simply works, and follows the UNIX tradition of single-purpose tools that do one thing well.
Unlike other similar tools, pyenv does not depend on Python itself. Having been made from pure shell scripts, it's safe from a Python bootstrap problem. It doesn't need to be loaded...