def METHOD_NAME(self):
    # test correctness
    x = list(range(10))
    itr = iterators.GroupedIterator(x, 1)
    self.assertEqual(list(itr), [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9]])
    itr = iterators.GroupedIterator(x, 4)
    self.assertEqual(list(itr), [[0, 1, 2, 3], [4, 5, 6, 7], [8, 9]])
    itr = iterators.GroupedIterator(x, 5)
    self.assertEqual(list(itr), [[0, 1, 2, 3, 4], [5, 6, 7, 8, 9]])
    # test the GroupIterator also works correctly as a CountingIterator
    x = list(range(30))
    ref = list(iterators.GroupedIterator(x, 3))
    itr = iterators.GroupedIterator(x, 3)
    self.test_counting_iterator_index(ref, itr)