I'm passing all the test it throws at my code, but I keep getting the following exit error:

Traceback (most recent call last):
File "main.py", line 21, in
test.assert_equals(comp(a1, a2), False)
File "/home/codewarrior/solution.py", line 3, in comp
array2.sort()
AttributeError: 'NoneType' object has no attribute 'sort'

I know what the problem is in the use of the sort() method but what's the best way of rectifying the problem? Any feedback would be greatly appreciated, thanks! :)