Emacs: Distinguish between Python 2.x and 3.x in emacs

I use Emacs and am currently working on projects that use different versions of Python 开发者_运维知识库(2.x and 3.x) and both have different sets of documentation and different interactive shells.

I want to be able to distinguish between these versions in Emacs (so I read the right documentation with pylookup and also setup the correct interactive shell). How can I do this in Emacs?

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See this older question: Both Python 2 and 3 in Emacs