Because the only methods required of an iterator are __next__ and __iter__, there is no way to check whether there are remaining items, other than to call next() and catch StopIteration. Also, it’s not possible to “reset” an iterator. If you need to start over, you need to call iter() on the iterable that built the iterator in the first place. Calling iter() on the iterator itself won’t help either, because—as mentioned—Iterator.__iter__ is implemented by returning self, so this will not reset a depleted iterator.
