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: frontend.go
    path of file: ./repos/plumber/vendor/github.com/jackc/pgx/pgproto3
    
    the code of the file until where you have to start completion: package pgproto3

import (
	"encoding/binary"
	"io"

	"github.com/jackc/pgx/chunkreader"
	"github.com/pkg/errors"
)

type Frontend struct {
	cr *chunkreader.ChunkReader
	w  io.Writer

	// Backend message flyweights
	authentication
    
func (b *Frontend) Receive() (BackendMessage, error) {
	if !b.partialMsg {
		header, err := b.cr.Next(5)
		if err != nil {
			return nil, err
		}

		b.msgType = header[0]
		b.bodyLen = int(binary.BigEndian.Uint32(header[1:])) - 4
		b.partialMsg = true
	}

	var msg BackendMessage
	switch b.msgType {
	case '1':
		msg = &b.parseComplete
	case '2':
		msg = &b.bindComplete
	case '3':
		msg = &b.closeComplete
	case 'A':
		msg = &b.notificationResponse
	case 'c':
		msg = &b.copyDone
	case 'f':
		msg = &b.copyFail
	case 'C':
		msg = &b.commandComplete
	case 'd':
		msg = &b.copyData
	case 'D':
		msg = &b.dataRow
	case 'E':
		msg = &b.errorResponse
	case 'G':
		msg = &b.copyInResponse
	case 'H':
		msg = &b.copyOutResponse
	case 'I':
		msg = &b.emptyQueryResponse
	case 'K':
		msg = &b.backendKeyData
	case 'n':
		msg = &b.noData
	case 'N':
		msg = &b.noticeResponse
	case 'R':
		msg = &b.authentication
	case 'S':
		msg = &b.parameterStatus
	case 't':
		msg = &b.parameterDescription
	case 'T':
		msg = &b.rowDescription
	case 'V':
		msg = &b.functionCallResponse
	case 'W':
		msg = &b.copyBothResponse
	case 'Z':
		msg = &b.readyForQuery
	case 's':
		msg = &b.portalSuspended
	default:
		return nil, errors.Errorf("unknown message type: %c", b.msgType)
	}

	msgBody, err := b.cr.Next(b.bodyLen)
	if err != nil {
		return nil, err
	}

	b.partialMsg = false

	err = msg.Decode(msgBody)
	return msg, err
}