• Problem: plistlib can't read/write binary plists (<3.4)
• Solution: pip install biplist
It's a drop-in replacement of py2's plistlib, and it handles XML plists too by calling through to plistlib.

• Problem: os.makedirs doesn't have exist_ok (<3.2)
• Solution: catch the error and ignore it if it's EEXIST. StackOverflow answer
Why not use pathlib2, like the top answer suggests? Because it's not a perfect port and can't handle non-ASCII paths, thanks to the difference in Unicode/string handling between py2 and py3.

• Problem: no enum (<3.4)
• Solution: pip install enum34

• Problem: no os.walk (<2.3)
• Solution: use os.path.walk
This is useful for PyS60 1.4.5 because that uses Python 2.2. Note that the code needs to be adapted, as os.path.walk uses a callback function.