code: func (fs *RootMappingFs) Stat(name string) (os.FileInfo, error) {
  	if fs.isRoot(name) {
  		return newRootMappingDirFileInfo(name), nil
  	}
  	realName := fs.realName(name)
  
  	fi, err := fs.Fs.Stat(realName)
  	if rfi, ok := fi.(RealFilenameInfo); ok {
  		return rfi, err
  	}
  
  	return &realFilenameInfo{FileInfo: fi, realFilename: realName}, err
  
  }
docs: // Stat returns the os.FileInfo structure describing a given file.  If there is
  // an error, it will be of type *os.PathError.