Wouldn't that require some code to redefine `int.__add__` or `int.__radd__` between iterations of the loop? Which I would file under "bizarre shit that shouldn't normally happen." Before the loop starts, you'd have to override `int.__add__` to modify itself every time it's called, or something crazy.

If we're talking about custom classes and not ints, maybe it's a bigger problem. But if PyPy doesn't allow the required introspection to make this work, how does it run anything at all?