anchor.diff:    // terminal size normally 80x24. Two lines are used for the prompts
     // before and after running the compiler.
     print('''
  -dart2js [OPTIONS...] DART-FILE
  -
  -A Dart to JavaScript compiler.
  -
  -By default, the compiled JavaScript code is saved to a file named
  -out.js in the current directory.
  +Usage: dart2js [OPTIONS] DARTFILE
  +
  +Compiles Dart to JavaScript.
   
   Common options:
  -
     --help      Display this message.
  -
  -  --out=FILE  Save the output to FILE (default is out.js).
  -
  -  --checked   Turn on checked mode in generated JavaScript code.
  -''');
  +  --out=FILE  Save the output to FILE (default: out.js).
  +  --checked   Turn on checked mode in generated JavaScript code.''');
   }
   
   void helpAndExit() {
  
positive.code:     new OptionHandler('--help', (_) => helpAndExit()),
      // The following two options must come last.
      new OptionHandler('-.*', (String argument) {
        fail('Error: unknown option "$argument".');
      }),
      new OptionHandler('.*', (String argument) {
        arguments.add(nativeToUriPath(argument));
  
negative.code:   Uri libraryRoot = cwd;
    Uri out = cwd.resolve('out.js');
    List<String> options = new List<String>();
    bool explicitOut = false;
  
    passThrough(String argument) => options.add(argument);
  
  