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: backups.go
    path of file: ./repos/juju/state/backups
    
    the code of the file until where you have to start completion: // Copyright 2014 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.

package backups

import (
	"fmt"
	"io"
	"io/fs"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/dustin/go-humanize"
	"github.com/juju/errors"
	"github.com/juju/loggo"
	"github.com/juju/utils/v3/du"
)

const (
	// FilenamePrefix is the prefix used for backup archive files.
	FilenamePrefix = "juju-backup
    
func isValidFilepath(root string, filePath string) (bool, error) {
	if !filepath.IsAbs(filePath) {
		return false, nil
	}
	if !strings.HasPrefix(filepath.Base(filePath), FilenamePrefix) {
		return false, nil
	}
	result := false
	err := filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
		if d.IsDir() {
			return nil
		}
		if path == filePath {
			result = true
			return nil
		}
		return nil
	})
	return result, err
}