LatestOnly   bool                     // returns only latest versions for all matching objects
	AskDisks     string                   // dictates how many disks are being listed
	VersionsSort WalkVersionsSortOrder    // sort order for versions of the same object; default: Ascending order in ModTime
	Limit        int                      // maximum number of items, 0 means no limit
}

			err := api.Walk(ctx, r.Bucket, prefix, prefixResultCh, WalkOptions{
				Marker:       lastObject,
				LatestOnly:   false, // we need to visit all versions of the object to implement purge: retainVersions
				VersionsSort: WalkVersionsSortDesc,
			})
			if err != nil {
				cancelCause(err)
				xioutil.SafeClose(results)
				return
			}
			for result := range prefixResultCh {
				results <- result
			}
		}