Check whether the alphabetical array is a subset of another alphabetical array. RUNNING TIME O(n)

answer1.py

import string
def isSubset(arr1,arr2):
    d = dict.fromkeys(string.ascii_lowercase, 0)
    for i in arr1:
        d[i]+=1

    for j in arr2:
        if d[j] == 0:
            return False

    return True

print(isSubset(['a','b','c'],['c','b','z']))