You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: message.go
    path of file: ./repos/sliver/implant/vendor/gopkg.in/jcmturner/gokrb5.v7/kadmin
    
    the code of the file until where you have to start completion: package kadmin

import (
	"bytes"
	"encoding/binary"
	"errors"
	"fmt"
	"math"

	"gopkg.in/jcmturner/gokrb5.v7/messages"
	"gopkg.in/jcmturner/gokrb5.v7/types"
)

const (
	verisonHex = "ff80"
)

// Request message for changing password.
type Request struct {
	APREQ   messages.APReq
	KRBPriv messages.KRBPriv
}

// Reply message for a password change.
type Reply struct {
	MessageLength int
	Version       int
	APREPLength   int
	APREP         messages.APRep
	KRBPriv       messages.KRBPriv
	KRBError      messages.KRBError
	IsKRBError    bool
    
func (m *Reply) Unmarshal(b []byte) error {
	m.MessageLength = int(binary.BigEndian.Uint16(b[0:2]))
	m.Version = int(binary.BigEndian.Uint16(b[2:4]))
	if m.Version != 1 {
		return fmt.Errorf("kadmin reply has incorrect protocol version number: %d", m.Version)
	}
	m.APREPLength = int(binary.BigEndian.Uint16(b[4:6]))
	if m.APREPLength != 0 {
		err := m.APREP.Unmarshal(b[6 : 6+m.APREPLength])
		if err != nil {
			return err
		}
		err = m.KRBPriv.Unmarshal(b[6+m.APREPLength : m.MessageLength])
		if err != nil {
			return err
		}
	} else {
		m.IsKRBError = true
		m.KRBError.Unmarshal(b[6:m.MessageLength])
		m.ResultCode, m.Result = parseResponse(m.KRBError.EData)
	}
	return nil
}