--ini-enunciat

>>> from countdown import comptar_enrere

>>> itr = comptar_enrere(iter([3, 5, 2, 8]))
>>> for x in itr:
...    print(x, end=',')
3,2,1,5,4,3,2,1,2,1,8,7,6,5,4,3,2,1,
>>> next(itr, 'final')
'final'

--fi-enunciat

>>> itr = comptar_enrere(iter([1, 10, 2, 4, 8, 1]))
>>> for x in itr:
...    print(x, end=',')
1,10,9,8,7,6,5,4,3,2,1,2,1,4,3,2,1,8,7,6,5,4,3,2,1,1,

>>> itr = comptar_enrere(iter(range(1,20,3)))
>>> for x in itr:
...    print(x, end=',')
1,4,3,2,1,7,6,5,4,3,2,1,10,9,8,7,6,5,4,3,2,1,13,12,11,10,9,8,7,6,5,4,3,2,1,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,