Practicing for my interview, I am working on some problems in Python.

This problem is to decide two strings are permutation (or anagrams) of each each other.

```
def is_permutation(first, second):
    if len(first) != len(second):
        return False
    first_arr = [0 for i in range(256)] # ASCII size
    second_arr = [0 for i in range(256)] # ASCII size
    for i in range(len(first)):
        first_arr[ord(first[i])] += 1
        second_arr[ord(second[i])] += 1
    if first_arr != second_arr:
        return False
    else:
        return True

```

I feel this code can be *more efficient*, but I cannot make it. Can anybody give me advice or tip so that I can improve please?