Annotate the standard library
Currently, absolutely none of the standard library is annotated. In order to make Rtc useful, we need to annotate the type of the standard library. For this issue to be totally resolved, we'll need to address #5 and #11 (we can fake #5 for now by mutating the type_parameters property of the nominal types).
Optionally, we should support #12 (for better annotations). In order for these standard library annotations to be used effectively, we should also implement #9.
Now that rtc is much more mature, I think it's time to bite the bullet and get this done.
How about to have repository for type definitions like https://github.com/flowtype/flow-typed