My code is working, but I want to remove "None" from the output. How can I do it?

```py
def permutation(a,b):
    c = sorted(a)
    d = sorted(b)

    if c == d :
        return print(a," and ", b ," are permutations")
    else:
        count = 0
        for i in c:
            if c in d:
                d.remove(d.index(c))
            else:
                count = count + 1
        return print(a, " and ", b, " are NOT permutations; no. of differences = ", count)

print(permutation([10, 9, 11, 1] , [9,1,11,10] ))
print(permutation([10, 9, 1, 10] , [8,1,11,10]))

```

This is my output:

```none
[10, 9, 11, 1]  and  [9, 1, 11, 10]  are permutations
None
[10, 9, 1, 10]  and  [8, 1, 11, 10]  are NOT permutations; no. of differences =  4
None

```