"When in Rome, do as the Roman's do."

I wouldn't try to hack a Python parser with regexes.

When confronted with a similar task for Perl I'd try to hack B::Deparse or PPI to do the heavy lifting for me.

I'm no expert for Python and dunno the most similar tool to B::Deparse, but a short search showed me they have

• Lint tools
• Pretty printers
• an AST tree class
• Decompilers

... so plenty of possibilities for code analysis.

Maybe you should ask at a Python board for assistance?

HTH! :)