code: def _const_compare_digest_backport(a, b):
      
      result = abs(len(a) - len(b))
      for l, r in zip(bytearray(a), bytearray(b)):
          result |= l ^ r
      return result == 0
docs: Compare two digests of equal length in constant time.
  
      The digests must be of type str/bytes.
      Returns True if the digests match, and False otherwise.