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
