anchor.diff:      test('success', () {
         final lines = <String>[];
         expect(
  -          progress(identifier, (line) => lines.add(line))
  +          progress(identifier, lines.add)
                 .parse('ab123')
                 .isSuccess,
             isTrue);
  
positive.code:     test('failure', () {
        final lines = <String>[];
        expect(
            progress(identifier, (line) => lines.add(line)).parse('1').isFailure,
            isTrue);
        expect(lines, [
          '* Instance of \'SequenceParser\'',
  
negative.code:     test('failure', () {
        final lines = <String>[];
        expect(
            profile(identifier, lines.add).parse('1').isFailure,
            isTrue);
        expect(lines, hasLength(4));
        final splitLines = lines.map((row) => row.split('\t'));
  