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: idtools_unix.go
    path of file: ./repos/docker-ce/components/cli/vendor/github.com/docker/docker/pkg/idtools
    
    the code of the file until where you have to start completion: // +build !windows

package idtools // import "github.com/docker/docker/pkg/idtools"

import (
	"bytes"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strconv"
	"sync"
	"syscall"

	"gith
    
func LookupGroup(name string) (user.Group, error) {
	// first try a local system files lookup using existing capabilities
	group, err := user.LookupGroup(name)
	if err == nil {
		return group, nil
	}
	// local files lookup failed; attempt to call `getent` to query configured group dbs
	return getentGroup(name)
}