[newaccoutnas]

In addition I don't think you'd have to interrogate every line, depending on your codebase and upstream module support for Python 3. There are tools like:

http://python-future.org/automatic_conversion.html and https://python-modernize.readthedocs.io/en/latest/

Which should get you most of the way there. Look at https://docs.python.org/3/howto/pyporting.html for more info