code: def compare(self, digest_2, is_hex = False):
          
          # convert hex string to list of ints
          if is_hex:
              digest_2 = convert_hex_to_ints(digest_2)
  
          bit_diff = 0
          for i in range(len(self.digest)):
              bit_diff += POPC[self.digest[i] ^ digest_2[i]]           #computes the bit diff between the i'th position of the digests
  
          return 128 - bit_diff
docs: returns difference between the nilsimsa digests between the current
          object and a given digest