code: func hasDirPrefix(dirPrefix, fullpath string) bool {
  	if !strings.HasPrefix(fullpath, dirPrefix) {
  		return false
  	}
  	if len(fullpath) == len(dirPrefix) {
  		return true
  	}
  	if fullpath[len(dirPrefix)] == filepath.Separator {
  		return true
  	}
  	return false
  }
docs: // hasDirPrefix reports whether the path has the provided directory prefix.
  // Both should be absolute paths.