Message 257277 - Python tracker

I don’t think you need to define __len__() to get an iterable, only __getitem__().

Also, if I understand your problem, Container would also be susceptible in theory, because membership testing via “in” and “not in” falls back to iteration. If you only define __getitem__(), your class is both iterable and a container, but it is neither an Iterable nor a Container. :)