90% accuracy was just my own hunch but it is true that, out of 2000 lines, roughly 200 lines were changed, and there were roughly 20 mypy errors left after the

90% accuracy was just my own hunch but it is true that, out of 2000 lines, roughly 200 lines were changed, and there were roughly 20 mypy errors left after the first fully automatic pass. Most of these were due to code that did use duck typing, but it turned out that this was dead code and therefore it's understandable that the LLM got confused. Once the dead code was removed, the remaining 5 or so issues were annotations that were too loose in either variable or argument declarations. It would have taken at least a couple hours to do it by hand.