code: public static void renderIndex(final PrintWriter out, final Collection<? extends HelpPage> pages) {
      checkNotNull(out);
      checkNotNull(pages);
  
      checkArgument(!pages.isEmpty(), "No help pages to render index");
  
      // construct a printf format with sizing for showing columns
      int max = pages.stream().mapToInt(page -> page.getName().length()).max().orElse(0);
      String nameFormat = "%-" + max + 's';
  
      for (HelpPage page : pages) {
        String formattedName = String.format(nameFormat, page.getName());
        out.format("  @{bold %s}", formattedName);
  
        String description = page.getDescription();
        if (description != null) {
          out.printf("   %s%n", description);
        }
        else {
          out.println();
        }
      }
    }
docs: Render a column-formatted index of help pages.