But you can't do that with Transcrypt, either. Both are "not quite python" and won't run regular python code. There is very little difference between the goal of the two projects.
"Known restrictions...No standard libs...Not all methods of builtin types are there by default...No iterator, generator, xrange stuff."
There's also the fact that everything is still, at the core, pure javascript. For example you can't print("string" * 10) or even iterate over a dictionary.
I'm not saying this to put down the project - I am very interested in it - but it cannot parse pure python, and that isn't the goal of the project.
Granted, there are restrictions. However, a lot of those restrictions have disappeared in recent releases, and more are disappearing all the time. Iterators, generators, xrange, I expect those all to be included in due time. Additionally, re: the standard library, there is a project called Ouroboros[1] that replicates the standard library in pure python, and there was discussion regarding integrating that into Transcrypt.
You're right, it's not there yet, and I'm interested in it for purely theoretical reasons (I personally don't think I'd ever use Transcrypt for anything in production), but I think it holds great potential.