# Your goal in this kata is to implement a difference function, which subtracts one list from another and returns the result.
#
# It should remove all values from list a, which are present in list b.
#
# array_diff([1,2],[1]) == [2]
# If a value is present in b, all of its occurrences must be removed from the other:
#
# array_diff([1,2,2,2,3],[2]) == [1,3]

x=[1,2,2,3]
x2=[2]
def array_diff(a, b):
    for i in b:
        while i in a:
            del a[a.index(2)]
    return a

print(array_diff(x,x2))