Larry, if this version looks good to you, I'd like to commit it.

- id() is now back to being a properly generated AC function (since AC can now preserve the old C level signature)

- sorted() is partially converted and has a __text_signature__ compatible docstring. However, full conversion will have to wait for the ability to preserve the kwds dict, since that's the API exposed by the list object.

- with the new never-triggered-by-accident AC syntax, the test case now ensures that all the builtins that are expected to *not* expose signature info at this point, don't. As they're converted for 3.5, that will force them to be added to the list of functions that are checked for compatibility.

I'm thinking it's probably worth flagging this new test as a CPython implementation detail test, though.