code: func dataToAuth(version byte, public []byte, state []byte) [][]byte {
  	out := [][]byte{
  		{version},
  		public,
  	}
  	if len(state) != 0 {
  		out = append(out, state)
  	}
  	return out
  }
docs: // dataToAuth generates list of byte blobs authenticated by MAC.