input: Write a python function to calculate the Hamming distance between two strings of equal length.
  assert hammingDistance("Hello World!", "Goodbye World!") == 5
  assert hammingDistance("10101", "10011") == 2
  assert hammingDistance("karolin", "kathrin") == 3
output: def hammingDistance(s1, s2):
      return sum(c1 != c2 for c1, c2 in zip(s1, s2))