--ini-enunciat

>>> from anterior import modifica

>>> itr = modifica(iter([3, 5, 2, 8]), [2, 4])
>>> for x in itr:
...    print(x, end=',')
12,30,
>>> next(itr, 'final')
'final'
>>> itr2 = modifica(iter([3, 5, 2, 8]), [1, 5])
>>> for x in itr2:
...    print(x, end=',')
12,6,72,
>>> next(itr2, 'final')
'final'

--fi-enunciat

>>> itr2 = modifica(iter(range(20, 1, -2)), [5])
>>> for x in itr2:
...    print(x, end=',')
420,342,272,210,156,110,72,42,20,6,
>>> itr2 = modifica(iter(range(30)), [0, 3, 4, 7])
>>> for x in itr2:
...    print(x, end=',')
2,12,20,30,42,56,90,132,182,210,240,272,306,380,462,552,600,650,702,756,870,
>>> itr2 = modifica(iter(range(50)), [0, 1, 2, 3, 4, 5, 6, 7, 8])
>>> for x in itr2:
...    print(x, end=',')
12,56,182,306,552,756,1122,1406,1892,2256,