code: func C128ProofOfWork(trytes Trytes, mwm int, parallelism ...int) (Trytes, error) {
  	return c128ProofOfWork(trytes, mwm, nil, parallelism...)
  }
docs: // PoWC128 does Proof-of-Work on the given trytes using native C code and __int128 C type.
  // This implementation follows common C standards and does not rely on SSE which is AMD64 specific.