def METHOD_NAME(self):
    load_pattern = fetch('data/no_time_for_that_tiny.gif')
    def load_fn(f, step):
        vid = iio3.imiter(f)
        return list(itertools.islice(vid, None, None, step))
    ic = ImageCollection(load_pattern, load_func=load_fn, step=3)
    # Each file should map to one image (array).
    assert len(ic) == 1
    # GIF file has 24 frames, so 24 / 3 equals 8.
    assert len(ic[0]) == 8