if err := api.Walk(ctx, r.Source.Bucket, prefix, prefixWalkCh, WalkOptions{
					Marker:   lastObject,
					Filter:   selectObj,
					AskDisks: walkQuorum,
				}); err != nil {
					cancelCause(err)
					xioutil.SafeClose(walkCh)
					return
				}
				for obj := range prefixWalkCh {
					walkCh <- obj
				}
			}
			xioutil.SafeClose(walkCh)
		}()

			return nil
		}

		if s.walkMu != nil {
			s.walkMu.Lock()
		}
		entries, err := s.ListDir(ctx, "", opts.Bucket, current, -1)
		if s.walkMu != nil {
			s.walkMu.Unlock()
		}
		if err != nil {
			// Folder could have gone away in-between
			if err != errVolumeNotFound && err != errFileNotFound {
				internalLogOnceIf(ctx, err, "metacache-walk-scan-dir")
			}

		f.walk(n.Body, ctxTypeSwitch, visit)
	case *ast.CommClause:
		f.walk(n.Comm, ctxStmt, visit)
		f.walk(n.Body, ctxStmt, visit)
	case *ast.SelectStmt:
		f.walk(n.Body, ctxStmt, visit)
	case *ast.ForStmt:
		f.walk(n.Init, ctxStmt, visit)
		f.walk(&n.Cond, ctxExpr, visit)
		f.walk(n.Post, ctxStmt, visit)
		f.walk(n.Body, ctxStmt, visit)
	case *ast.RangeStmt:
		f.walk(&n.Key, ctxExpr, visit)

}

func NewWalker(context *build.Context, root string) *Walker {
	w := &Walker{
		context:  context,
		root:     root,
		features: map[string]bool{},
		imported: map[string]*apiPackage{"unsafe": &apiPackage{Package: types.Unsafe}},
	}
	w.loadImports()
	return w
}

func (w *Walker) Features() (fs []string) {
	for f := range w.features {
		fs = append(fs, f)
	}

   * </pre>
   *
   * @throws IllegalArgumentException if there is a loop in the causal chain
   */
  public static Throwable getRootCause(Throwable throwable) {
    // Keep a second pointer that slowly walks the causal chain. If the fast pointer ever catches
    // the slower pointer, then there's a loop.
    Throwable slowPointer = throwable;
    boolean advanceSlowPointer = false;

    Throwable cause;

        List<Path> poms;

        @Setup(Level.Iteration)
        public void setUp() throws IOException {
            Path userHome = Paths.get(System.getProperty("user.home"));
            poms = Files.walk(userHome.resolve(".m2/repository/org/apache/maven"))
                    .filter(p -> p.getFileName().toString().endsWith(".pom"))
                    .collect(Collectors.toList());
        }
    }

    @Benchmark

	ListObjectVersions(ctx context.Context, bucket, prefix, marker, versionMarker, delimiter string, maxKeys int) (result ListObjectVersionsInfo, err error)
	// Walk lists all objects including versions, delete markers.
	Walk(ctx context.Context, bucket, prefix string, results chan<- itemOrErr[ObjectInfo], opts WalkOptions) error

	// Object operations.

	// GetObjectNInfo returns a GetObjectReader that satisfies the

	ListVols(ctx context.Context) (vols []VolInfo, err error)
	StatVol(ctx context.Context, volume string) (vol VolInfo, err error)
	DeleteVol(ctx context.Context, volume string, forceDelete bool) (err error)

	// WalkDir will walk a directory on disk and return a metacache stream on wr.
	WalkDir(ctx context.Context, opts WalkDirOptions, wr io.Writer) error

	// Metadata operations

	}

	if err := scanner.Err(); err != nil {
		return nil, err
	}

	return result, nil
}

func getDiskUUIDMap() (map[string]string, error) {
	result := make(map[string]string)
	err := filepath.Walk("/dev/disk/by-uuid/",
		func(path string, info os.FileInfo, err error) error {
			if err != nil {
				return err
			}
			realPath, err := filepath.EvalSymlinks(path)
			if err != nil {
				return err
			}

		sort.Strings(closestCommands)
		// Suggest other close commands - allow missed, wrongly added and
		// even transposed characters
		for _, value := range commandsTree.Walk(commandsTree.Root()) {
			if sort.SearchStrings(closestCommands, value) < len(closestCommands) {
				continue
			}
			// 2 is arbitrary and represents the max
			// allowed number of typed errors