code: def hamming_distance(self, another):
          
          x = (self.hash ^ another) & ((1 << self.hash_bit_number) - 1)
          result = 0
          while x:
              result += 1
              x &= x - 1
          return result
docs: Compute hamming distance,hamming distance is a total number of different bits of two binary numbers.
  
          :param another: another simhash value.
          :return: a hamming distance that current simhash and another simhash.