The easiest way to do this is use sets. Sets will take the lists and take only unique values. Then you can perform a & operation that acts like intersection to get the common objects from the lists.
example
>>> a = [1, 2, 3, 4, 5]
>>> b = [9, 8, 7, 6, 5]
>>> set(a) & set(b)
{5}You can also use set.intersection function to perform this operation.
example
>>> a = [1, 2, 3, 4, 5] >>> b = [9, 8, 7, 6, 5] >>> set(a).instersection(set(b)) set([5])