Intersection of two lists including duplicates?

>>> a = [1,1,1,2,3,4,4]>>> b = [1,1,2,3,3,3,4][1,1,2,3,4]

Please note this is not the same question as this:Python intersection of two lists keeping duplicatesBecause even though there are three 1s in list a, there are only two in list b so the result should only have two.