on a system w/o python3

[Skaperen]

lots of my scripts work fine on python3.  a few even work better when run on python3.  only a few others need python2 and i hope to eventually recode those to get them working on python3.  about half now have a #! (hash-bang) to run python3.  but a problem i have is that the Amazon Linux distro i use for instances in the AWS cloud (Amazon Web Services) only has python2.  python3 won't install right (it is in the repository) due to conflicts.  and the system is very dependent on python so i can't uninstall python2 and reinstall python3.  i could run Ubuntu Linux like i do on my laptop but the Ubuntu Linux server edition available on AWS does not work with IPv6.  so i am stuck with Amazon Linux and stuck with python2.  that means half my scripts won't even run.  so i am trying to figure out a way to run them on python3 where that is available but have them run on python2 where that is the only version available.

before i follow up with my (perhaps silly) ideas, i want to find out if there are any solutions to this kind of problem that already exist.  i don't know what kind of search terms i could use on google for this.

out of curiosity, i'd like to know how Microsoft Windows deals with scripts using different interpreters.  does it support has-bang (#!) or have something equivalent?  can it even do a mix of python2 and python3?