You can check for the Python version in your code, to make sure your users are not running your script with an incompatible version. Use this simple check:
if not sys.version_info > (2, 7): # berate your user for running a 10 year # python version elif not sys.version_info >= (3, 5): # Kindly tell your user (s)he needs to upgrade # because you're using 3.5 features