merkle/simple_tree.go
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)
}
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)
}
// SimpleHashFromTwoHashes is the basic operation of the Merkle tree: Hash(left | right).