case "Marker":
			z.Marker, bts, err = msgp.ReadStringBytes(bts)
			if err != nil {
				err = msgp.WrapError(err, "Marker")
				return
			}
		case "LatestOnly":
			z.LatestOnly, bts, err = msgp.ReadBoolBytes(bts)
			if err != nil {
				err = msgp.WrapError(err, "LatestOnly")
				return
			}
		case "AskDisks":
			z.AskDisks, bts, err = msgp.ReadStringBytes(bts)
			if err != nil {

type WalkOptions struct {
	Filter       func(info FileInfo) bool // return WalkFilter returns 'true/false'
	Marker       string                   // set to skip until this object
	LatestOnly   bool                     // returns only latest versions for all matching objects
	AskDisks     string                   // dictates how many disks are being listed

	}

	ctx, cancel := context.WithCancel(ctx)
	defer cancel()

	results := make(chan ObjectInfo, workerSize)
	if err := api.Walk(ctx, r.Bucket, r.Prefix, results, WalkOptions{
		Marker:       lastObject,
		LatestOnly:   false, // we need to visit all versions of the object to implement purge: retainVersions
		VersionsSort: WalkVersionsSortDesc,
	}); err != nil {
		// Do not need to retry if we can't list objects on source.
		return err

						disks = disks[:askDisks]
					}

					requestedVersions := 0
					if opts.LatestOnly {
						requestedVersions = 1
					}
					loadEntry := func(entry metaCacheEntry) {
						if entry.isDir() {
							return
						}

						if opts.LatestOnly {
							fi, err := entry.fileInfo(bucket)
							if err != nil {
								cancel()
								return
							}