Could this be done with an IDE plugin (for Pycharm or whatnot)? It is tedious to go though code and carefully annotate each variable and run so many compile test, read error, revise, cycles. It should be possible on a per function basis to statically check how each variable relates to the inputs and outputs, and just annotate those. Then the plugin could solve the units for each item, and only ask for an annotation where needed to resolve an ambiguous case.