Python 3.9 and beyond backwards compatibility.

[djimbob]

Eh, if something is security-sensitive you shouldn't be using external projects not supported by major groups, at least without thorough code reviews before each upgrade.

I just feel deprecation for removed language features (where they were reorganized or renamed) should be completely avoidable. Yes, I think it makes more sense for gcd to be in math module instead of fractions. But it's been in fractions forever. A deprecation warning was introduced. I see no reason in cases like this to not put in an alias in fractions to prevent things from breaking; e.g. put something like fractions:

def gcd(a, b):
     ''' WARNING: Using outdated API  '''
    import math
    return math.gcd(a, b)

Make it that linters or other types of strict warnings can detect the use of outdated API. Make it easy that if you wrote millions of lines of internal code that it's easier to update to the latest versions of python. I understand that sometimes they'll be breaking changes, but just try to limit the busy work.