When I have time, I would like to re-launch a python-dev discussion on this.  It is my feeling that this solves an invented problem.  In my experience, it only ever happens to people who have intentionally trying to create this effect.

Adding this kind of "junk" through-out the code base adds complexity and more internal operations, but won't help *any* existing, deployed code.  We're making everyone pay for a problem that almost no one has.

Also, if we do care about interruptability, it is unclear whether the responsiblity should like with the consumer or the producer of the iterator.