// Other important fields are Limit, Marker.
// List ID always derived from the Marker.
func (z *erasureServerPools) listPath(ctx context.Context, o *listPathOptions) (entries metaCacheEntriesSorted, err error) {
	if err := checkListObjsArgs(ctx, o.Bucket, o.Prefix, o.Marker); err != nil {
		return entries, err
	}

	// Marker points to before the prefix, just ignore it.
	if o.Marker < o.Prefix {
		o.Marker = ""
	}

// all the contents of the provided bucket+prefix.
func (z *erasureServerPools) Walk(ctx context.Context, bucket, prefix string, results chan<- itemOrErr[ObjectInfo], opts WalkOptions) error {
	if err := checkListObjsArgs(ctx, bucket, prefix, ""); err != nil {
		xioutil.SafeClose(results)
		return err
	}
	parentCtx := ctx
	ctx, cancelCause := context.WithCancelCause(ctx)
	var entries []chan metaCacheEntry