anchor.diff:    group('progress', () {
       test('success', () {
         final lines = <String>[];
  -      expect(
  -          progress(identifier, lines.add)
  -              .parse('ab123')
  -              .isSuccess,
  -          isTrue);
  +      expect(progress(identifier, lines.add).parse('ab123').isSuccess, isTrue);
         expect(lines, [
           '* Instance of \'SequenceParser\'',
           '* Instance of \'CharacterParser\'[letter expected]',
  
positive.code:   group('trace', () {
      test('success', () {
        final lines = <String>[];
        expect(trace(identifier, lines.add).parse('a').isSuccess,
            isTrue);
        expect(lines, [
          'Instance of \'SequenceParser\'',
          '  Instance of \'CharacterParser\'[letter expected]',
  
negative.code:     });
      test('failure', () {
        final lines = <String>[];
        expect(progress(identifier, lines.add).parse('1').isFailure, isTrue);
        expect(lines, [
          '* Instance of \'SequenceParser\'',
          '* Instance of \'CharacterParser\'[letter expected]'
  