I\'m working with a large existing Python codebase and would like to start adding in type annotations so I can get some level of static checking. I\'m imagining something l
I don't know if this helps but for what it's worth, Jeremy Siek at U of Colorado did some work on gradual typing, and I found this doing a quick search. http://www.wiki.jvmlangsummit.com/pdf/28_Siek_gradual.pdf
My guess (I might be wrong) is there isn't any promising open source tools you can find at the moment since his research looks relatively new.
Your best bet might be to contact the authors and ask if they can release their code to you.