code: func printFlag(w io.Writer, f *flag.Flag) {
  	example, _ := flag.UnquoteUsage(f)
  	if example != "" {
  		fmt.Fprintf(w, "  -%s=<%s>\n", f.Name, example)
  	} else {
  		fmt.Fprintf(w, "  -%s\n", f.Name)
  	}
  
  	indented := wrapAtLength(f.Usage, 5)
  	fmt.Fprintf(w, "%s\n\n", indented)
  }
docs: // printFlag prints a single flag to the given writer.