docs: public static Shell createSubshell(String pathElement, Shell parent, String appName, Object mainHandler,
              MultiMap<String, Object> auxHandlers) {
  
          List<String> newPath = new ArrayList<String>(parent.getPath());
          newPath.add(pathElement);
  
          Shell subshell = new Shell(parent.getSettings().createWithAddedAuxHandlers(auxHandlers),
                  new CommandTable(parent.getCommandTable().getNamer()), newPath);
  
          subshell.setAppName(appName);
          subshell.addMainHandler(subshell, "!");
          subshell.addMainHandler(new HelpCommandHandler(), "?");
  
          subshell.addMainHandler(mainHandler, "");
          return subshell;
      }