anchor.diff:   *
    * A trivial test:
    *
  - *     #import('path-to-dart/pkg/unittest/unitest.dart');
  + *     import 'package:unittest/unittest.dart';
    *     main() {
    *       test('this is a test', () {
    *         int x = 2 + 3;
  
positive.code:  * that callback is run. A count argument can be provided to specify the number
   * of times the callback should be called (the default is 1).
   *
   *     #import('path-to-dart/pkg/unittest/unitest.dart');
   *     #import('dart:html');
   *     main() {
   *       test('calllback is executed once', () {
   *         // wrap the callback of an asynchronous call with [expectAsync0] if
   *         // the callback takes 0 arguments...
   *         window.setTimeout(expectAsync0(() {
   *           int x = 2 + 3;
   *           expect(x, equals(5));
   *         }), 0);
   *       });
   *
   *       test('calllback is executed twice', () {
   *         var callback = expectAsync0(() {
   *           int x = 2 + 3;
   *           expect(x, equals(5));
   *         }, count: 2); // <-- we can indicate multiplicity to [expectAsync0]
   *         window.setTimeout(callback, 0);
   *         window.setTimeout(callback, 0);
   *       });
   *     }
   *
  
negative.code:  *
   * Multiple tests:
   *
   *     import 'package:unittest/unittest.dart';
   *     main() {
   *       test('this is a test', () {
   *         int x = 2 + 3;
  