code: func New256() hash.Hash {
  	if h := new256Asm(); h != nil {
  		return h
  	}
  	return &state{rate: 136, outputLen: 32, dsbyte: 0x01}
  }
docs: // New256 creates a new SHA3-256 hash.
  // Its generic security strength is 256 bits against preimage attacks,
  // and 128 bits against collision attacks.