code: func (b *Bot) FileURLByID(fileID string) (string, error) {
  	f, err := b.FileByID(fileID)
  	if err != nil {
  		return "", err
  	}
  	return fmt.Sprintf("%s/file/bot%s/%s", b.URL, b.Token, f.FilePath), nil
  }
docs: // FileURLByID returns direct url for files using FileId which you can get from File object