docs: def ct_bytes_compare(a, b):
      """
      Constant-time string compare.
      http://codahale.com/a-lesson-in-timing-attacks/
      """
      if not isinstance(a, bytes):
          a = a.decode('utf8')
      if not isinstance(b, bytes):
          b = b.decode('utf8')
  
      if len(a) != len(b):
          return False
  
      result = 0
      for x, y in zip(a, b):
          result |= x ^ y
  
      return (result == 0)