We just migrated a big codebase to python 3 in about a year. It was not easy, but also not super hard with tools like futurize, and mypy. Gladly we already had

We just migrated a big codebase to python 3 in about a year. It was not easy, but also not super hard with tools like futurize, and mypy. Gladly we already had mypy hints, this helped us find a lot of mistakes when (not) using bytes. Now we're on python 3 we're auto-migrate the type hints to be inlined with tools, like com2ann https://github.com/ilevkivskyi/com2ann https://github.com/ilevkivskyi/com2ann And we're auto rewriting code to be more python 3 like with libcst and custom codemods...