keys/hd/address.go
func ComputePrivateKey(mprivHex string, chainHex string, path string, index int32) string {
	privKeyBytes := DerivePrivateKeyForPath(
		HexDecode(mprivHex),
		HexDecode(chainHex),
		fmt.Sprintf("%v/%v", path, index),
	)
	return HexEncode(privKeyBytes)
}
func ComputePrivateKey(mprivHex string, chainHex string, path string, index int32) string {
	privKeyBytes := DerivePrivateKeyForPath(
		HexDecode(mprivHex),
		HexDecode(chainHex),
		fmt.Sprintf("%v/%v", path, index),
	)
	return HexEncode(privKeyBytes)
}
// ComputePrivateKey returns the private key using the master mprivHex and chainCodeHex
// for the given path and index.