16. Annotating existing code

16.1. PyAnnotate

Listing 567. the -w flag means "go ahead, update the file"
$ pip install pyannotate
$ pyannotate -w FILE

16.2. monkeytype

$ pip install monkeytype
$ monkeytype run runtests.py
$ monkeytype stub some.module
$ monkeytype apply some.module