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: 7z.go
    path of file: ./repos/archiver
    
    the code of the file until where you have to start completion: package archiver

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"io/fs"
	"log"
	"path"
	"strings"

	"github.com/bodgit/sevenzip"
)

func init() {
	RegisterFormat(SevenZip{})

	// looks like the sevenzip package registers a lot of decompressors for us automatically:
	// https://github.com/bodgit/sevenzip/bl
    
func (z SevenZip) Match(filename string, stream io.Reader) (MatchResult, error) {
	var mr MatchResult

	// match filename
	if strings.Contains(strings.ToLower(filename), z.Name()) {
		mr.ByName = true
	}

	// match file header
	buf, err := readAtMost(stream, len(sevenZipHeader))
	if err != nil {
		return mr, err
	}
	mr.ByStream = bytes.Equal(buf, sevenZipHeader)

	return mr, nil
}