code: func ReMap(pattern string, replacement string) PathMapper {
  	re := regexp.MustCompile(pattern)
  	return func(filePath string) string {
  		if !re.MatchString(filePath) {
  			return ""
  		}
  		return re.ReplaceAllString(filePath, replacement)
  	}
  }
docs: // ReMap returns a PathMapper that compares file paths to the input pattern
  // and maps matches to the replacement string (see Regexp.ReplaceAllString).