code: func (f *FileResourceLookup) ResolvePath(path, relativeTo string) string {
  	vs := strings.SplitN(path, ":", 2)
  	if len(vs) != 2 || filepath.IsAbs(vs[0]) {
  		return path
  	}
  	vs[0] = relativePath(vs[0], relativeTo)
  	return strings.Join(vs, ":")
  }
docs: // ResolvePath returns the path to be used for the given path volume. This
  // function already takes care of relative paths.