code: func WalkFuncSkipFile(file os.FileInfo) error {
  	if file.IsDir() {
  		return filepath.SkipDir
  	}
  	// If we were to return SkipDir for a file, it would cause
  	// filepath.Walk to skip the file's containing directory, which we do
  	// not want (see https://golang.org/pkg/path/filepath/#WalkFunc).
  	return nil
  }
docs: // WalkFuncSkipFile is a helper for implemenations of filepath.WalkFunc. The
  // value that it returns may in turn be returned by the WalkFunc implementaiton
  // to indicate that file should be skipped.