Problem: We want a "globals" function.
There used to be a central list of globals: __all__.
But with modules it wasn't needed anymore.
We don't keep exports in a central list (but we might).

When working from Python source, a central list is easy to generated.
But when it includes JS, there may be multiple such lists.
And JS globals are also globals.

So the first question is: Can we ask a JS module what its globals are?
It doesn't have to be static, since that's also not the case in Python.
