2to3 -f all -f idioms -f buffer -f set_literal -f ws_comma foo.py
RefactoringTool: No changes to foo.py
RefactoringTool: Files that need to be modified:
According to Steven D'Aprano, this is a bug and the final line of text in your output should be interpreted as:
Files that include something that a fixer cares about, whether or not it gets modified.
In your case, the
foo.py code is perfectly compatible with Python 3 and no changes are needed as the first line of your output states.