code: def crypto_hash_sha512(message):
      
      digest = ffi.new("unsigned char[]", crypto_hash_sha512_BYTES)
      rc = lib.crypto_hash_sha512(digest, message, len(message))
      ensure(rc == 0,
             'Unexpected library error',
             raising=exc.RuntimeError)
      return ffi.buffer(digest, crypto_hash_sha512_BYTES)[:]
docs: Hashes and returns the message ``message``.
  
      :param message: bytes
      :rtype: bytes