code: func CommonLogHandler(logger *log.Logger, templ string, h http.Handler) http.Handler {
  	if logger == nil {
  		logger = log.New(os.Stdout, "", 0)
  	}
  	if templ == "" {
  		templ = CommonLogFormat
  	}
  
  	return &commonLogHandler{
  		handler:  h,
  		logger:   logger,
  		template: template.Must(template.New("").Parse(templ)),
  	}
  }
docs: // CommonLogHandler returns a handler that serves HTTP requests
  // If a logger is not provided, stdout will be used