input: Write a python function to calculate the Hamming distance between two strings.
  assert hammingDistance("karolin", "kathrin") == 3
  assert hammingDistance("karolin", "kerstin") == 3
  assert hammingDistance("1011101", "1001001") == 2
  assert hammingDistance("2173896", "2233796") == 3
output: def hammingDistance(str1, str2):
      if len(str1) != len(str2):
          raise ValueError("Strings must be of the same length")
      return sum(c1 != c2 for c1, c2 in zip(str1, str2))