code: func (r *regulator) URLFor(ctx context.Context, path string, options map[string]interface{}) (string, error) {
  	r.enter()
  	defer r.exit()
  
  	return r.StorageDriver.URLFor(ctx, path, options)
  }
docs: // URLFor returns a URL which may be used to retrieve the content stored at
  // the given path, possibly using the given options.
  // May return an ErrUnsupportedMethod in certain StorageDriver
  // implementations.