docs: public String usage()
      {
          StringBuilder sb = new StringBuilder( "Usage: " ).append( banner );
          if (options.isEmpty()) return sb.toString();
  
          sb.append( "\n\n" ).append( "Options:" );
          for (Option option : options)
          {
              sb.append( "\n" ).append( option );
          }
  
          return sb.toString();
      }