code: def constant_compare(a, b):
      
  
      if not isinstance(a, byte_cls):
          raise TypeError(pretty_message(
              '''
              a must be a byte string, not %s
              ''',
              type_name(a)
          ))
  
      if not isinstance(b, byte_cls):
          raise TypeError(pretty_message(
              '''
              b must be a byte string, not %s
              ''',
              type_name(b)
          ))
  
      if len(a) != len(b):
          return False
  
      if sys.version_info < (3,):
          a = [ord(char) for char in a]
          b = [ord(char) for char in b]
  
      result = 0
      for x, y in zip(a, b):
          result |= x ^ y
      return result == 0
docs: Compares two byte strings in constant time to see if they are equal
  
      :param a:
          The first byte string
  
      :param b:
          The second byte string
  
      :return:
          A boolean if the two byte strings are equal