Interpreter.run() should also accept a function, a method or a code object

[thedrow]

Right now, forcing the user to write explicit code when calling run() isn't convenient. We could accept a code object instead or fetch it from a callable using inspect.

[ericsnowcurrently]

This is a good idea, but one which will take a bunch more work than the minimal functionality PEP 554 specifies. See https://www.python.org/dev/peps/pep-0554/#interpreter-call.

We can circle back to this once PEP 554 is accepted and landed.