Does it make sense to draw some sort of parallel between next(myiterator, default="whatever") and mylist.pop(default="whatever")? They exhaust the iterator/list then start emitting the default argument (if provided).

Yep that's what I just did in my previous mail.

"""

I think the same way about set.pop, list.pop.

About .index I agree adding default= would make sense but that's not exactly the same thing as the others.
"""

Being picky: "TypeError: next() takes no keyword arguments", that's next(myierator, "whatever") ;)