code: func (fs FileServer) IsHidden(d os.FileInfo) bool {
  	// If the file is supposed to be hidden, return a 404
  	for _, hiddenPath := range fs.Hide {
  		// Check if the served file is exactly the hidden file.
  		if hFile, err := fs.Root.Open(hiddenPath); err == nil {
  			fs, _ := hFile.Stat()
  			hFile.Close()
  			if os.SameFile(d, fs) {
  				return true
  			}
  		}
  	}
  	return false
  }
docs: // IsHidden checks if file with FileInfo d is on hide list.