>>> def con_reverse(s):
... return s.reverse()
...
>>> def con_reversed(s):
... return reversed(s)
...
>>> ej = "Hola mundo".split()
>>> a = con_reversed(ej)
>>> a
<list_reverseiterator object at 0x1027eb198>
>>> ej
['Hola', 'mundo']
>>> b = con_reverse(ej)
>>> b
>>> ej
['mundo', 'Hola']