code: func SimpleHashFromTwoHashes(left, right []byte) []byte {
  	var hasher = tmhash.New()
  	err := encodeByteSlice(hasher, left)
  	if err != nil {
  			panic(err)
  		}
  	err = encodeByteSlice(hasher, right)
  	if err != nil {
  			panic(err)
  		}
  	return hasher.Sum(nil)
  }
docs: // SimpleHashFromTwoHashes is the basic operation of the Merkle tree: Hash(left | right).