print(beginning, middle, end)
() (0, 1, 2) (3, 4, 5, 6)
(0,) (1, 2, 3) (4, 5, 6)
(0, 1) (2, 3, 4) (5, 6)
(0, 1, 2) (3, 4, 5) (6,)
(0, 1, 2, 3) (4, 5, 6) ()

Note that *n* must be at least 0 and most equal to the length of
*iterable*.

This function will exhaust the iterable and may require significant
storage.
r