anchor.diff:    argParser.addOption("config",
         abbr: "c", allowMultiple: true, help: "Which configurations to run.");
     argParser.addFlag("help");
  +  argParser.addFlag("1",
  +      abbr: "1", help: "Run some of the 1.0-supporting configurations.");
  +  argParser.addFlag("2",
  +      abbr: "2", help: "Run the 2.0-supporting configurations.");
   
     var argResults = argParser.parse(arguments);
     if (argResults["help"] as bool) {
  
positive.code:     } else {
        passed.add(name);
      }
    }
  
    if (failed.length == 0) {
  
negative.code: }
  
  void usage(ArgParser parser) {
    print("Usage: dart run_tests.dart [--build] [-2] [-1] [--configs=...]"
        "<first file> [last file]");
    print("\n");
    print("Example:");
  