>>876
>>> L0 = [2, 2, 1, 0]
>>> L1 = [2, 3, 4]
>>> st0 = set(L0)
>>> st1 = set(L1)
>>> st2 = st0 - st1
>>> st2
{0, 1}
>>> L2 = []
>>> for x0 in L0:
... if x0 in st2:
... L2.append(x0)
...
>>> L2
[1, 0]