code: public static void acceptsNodeSingle(OptionParser parser) {
          parser.acceptsAll(Arrays.asList(OPT_N, OPT_NODE), "node id")
                .withRequiredArg()
                .describedAs("node-id")
                .ofType(Integer.class);
      }
docs: Adds OPT_N | OPT_NODE option to OptionParser, with one argument.
  
  @param parser OptionParser to be modified
  @param required Tells if this option is required or optional