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: fix_dat.go
    path of file: ./repos/seaweedfs/unmaintained/fix_dat
    
    the code of the file until where you have to start completion: package main

import (
	"flag"
	"fmt"
	"io"
	"os"
	"path"
	"strconv"

	"github.com/seaweedfs/seaweedfs/weed/glog"
	"github.com/seaweedfs/seaweedfs/weed/storage/backend"
	"github.com/seaweedfs/seaweedfs/weed/storage/needle"
	"github.com/seaweedfs/seaweedfs/weed/storage/super_block"
	"github.com/seaweedfs/seaweedfs/weed/storage/types"
	"github.com/seaweedfs/seaweedfs/weed/util"
)

var (
	fixVolumePath       = flag.String("dir", "/tmp", "data directory to store files")
	fixVolumeCollection = flag.String("collection", "", "the volume collection name")
	fixVolumeId         = flag.Int("volumeId", -1, "a volume id. The volume should already exist in the dir. The volume index file should not exist.")
)

/*
This is to resolve an one-time issue that caused inconsistency with .dat and .idx files.
In this case, the .dat file contains all da
    
func main() {
	flag.Parse()
	fileName := strconv.Itoa(*fixVolumeId)
	if *fixVolumeCollection != "" {
		fileName = *fixVolumeCollection + "_" + fileName
	}
	indexFile, err := os.OpenFile(path.Join(*fixVolumePath, fileName+".idx"), os.O_RDONLY, 0644)
	if err != nil {
		glog.Fatalf("Read Volume Index %v", err)
	}
	defer indexFile.Close()
	datFileName := path.Join(*fixVolumePath, fileName+".dat")
	datFile, err := os.OpenFile(datFileName, os.O_RDONLY, 0644)
	if err != nil {
		glog.Fatalf("Read Volume Data %v", err)
	}
	datBackend := backend.NewDiskFile(datFile)
	defer datBackend.Close()

	newDatFile, err := os.Create(path.Join(*fixVolumePath, fileName+".dat_fixed"))
	if err != nil {
		glog.Fatalf("Write New Volume Data %v", err)
	}
	defer newDatFile.Close()

	superBlock, err := super_block.ReadSuperBlock(datBackend)
	if err != nil {
		glog.Fatalf("Read Volume Data superblock %v", err)
	}
	newDatFile.Write(superBlock.Bytes())

	iterateEntries(datBackend, indexFile, func(n *needle.Needle, offset int64) {
		fmt.Printf("needle id=%v name=%s size=%d dataSize=%d\n", n.Id, string(n.Name), n.Size, n.DataSize)
		_, s, _, e := n.Append(datBackend, superBlock.Version)
		fmt.Printf("size %d error %v\n", s, e)
	})

}