Quick Check: Python Iterators

Review

1. Which statement best describes an iterable?

   An iterable can be passed to iter() or used by a for loop.
2. What does next(iterator) normally do?

   next() advances the iterator and returns its next value.
3. What signals normal completion of an iterator?

   StopIteration tells iteration machinery that there are no more values.
4. Why can a for loop consume many different kinds of objects?

   The for statement obtains and consumes an iterator from its iterable.
5. Why does a class-based iterator usually store a current position?

   An iterator must retain enough state to know what value should be produced next.
6. What does iter(callable, sentinel) do?

   The two-argument form constructs an iterator that calls the callable without arguments. A result equal to the sentinel signals completion and is not included in the values yielded by the iterator.