anchor.diff:    String indent(String s) => s.splitMapJoin('\n', onNonMatch: (n) => '    $n');
   
     sections.forEach((section, examples) {
  +    if (specifiedSection != null && section != specifiedSection) {
  +      return;
  +    }
       for (var e in examples) {
         var output;
         var nestedMap =
  
positive.code: import 'dart:io';
  import 'dart:mirrors';
  
  import 'package:collection/collection.dart';
  import 'package:html/parser.dart' show parseFragment;
  import 'package:markdown/markdown.dart';
  
negative.code:     .path);
  
  void main(List<String> args) {
    final parser = new ArgParser()
      ..addOption('section', help: 'Restrict tests to one section')
      ..addFlag('raw', defaultsTo: false, help: 'raw JSON format')
      ..addFlag('verbose', defaultsTo: false, help: 'verbose output');
    var options = parser.parse(args);
  
    var specifiedSection = options['section'];
    var raw = options['raw'];
    var verbose = options['verbose'];
  
    var sections = loadCommonMarkSections();
  
  