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: mpls.go
    path of file: ./repos/hubble-ui/backend/vendor/github.com/google/gopacket/layers
    
    the code of the file until where you have to start completion: // Copyright 2012 Google, Inc. All rights reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the LICENSE file in the root of the source
// tree.

package layers

import (
	"encoding/binary"
	"errors"
	"github.com/google/gopacket"
)

// MPLS is the MPLS packet header.
type MPLS struct {
	BaseLayer
	Label        uint32
	TrafficClass uint8
	StackBottom  bool
	TTL          uin
    
func (ProtocolGuessingDecoder) Decode(data []byte, p gopacket.PacketBuilder) error {
	switch data[0] {
	// 0x40 | header_len, where header_len is at least 5.
	case 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f:
		return decodeIPv4(data, p)
		// IPv6 can start with any byte whose first 4 bits are 0x6.
	case 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f:
		return decodeIPv6(data, p)
	}
	return errors.New("Unable to guess protocol of packet data")
}