Find the penultimate element of a list

Define a function penultimate which returns the "last but one" (or "penultimate") element of a list.

>>> a_list = [0, 1, 2, 3, 4, 5, 6, 7]
>>> penultimate(a_list)
6
>>> another_list = ['a', 'b', 'c', 'd', 'e', 'f']
>>> penultimate(another_list)
'e'
Solution
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