code: func NewMAC(outBytes uint8, key []byte) hash.Hash {
  	d, err := New(&Config{Size: outBytes, Key: key})
  	if err != nil {
  		panic(err.Error())
  	}
  	return d
  }
docs: // NewMAC returns a new hash.Hash computing BLAKE2b prefix-
  // Message Authentication Code of the given size in bytes
  // (up to 64) with the given key (up to 64 bytes in length).