anchor.diff:  // Welcome to Dart ;-)
   class IsInstanceOfTypeMatcher extends BaseMatcher {
     Type t;
  -  
  +
     IsInstanceOfTypeMatcher(Type t) {
       this.t = t;
     }
  -  
  -  bool matches(obj, MatchState matchState) {
  +
  +  bool matches(obj, Map matchState) {
       return reflect(obj).type.qualifiedName == reflectClass(t).qualifiedName;
     }
  -  
  +
     Description describe(Description description) =>
       description.add('an instance of ${t.toString()}');
   }
  
positive.code:   const ThrowsMatcher([Matcher matcher]) : _matcher = matcher, super(matcher);
  
    Description describeMismatch(item, Description mismatchDescription,
                                 MatchState matchState,
                                 bool verbose) {
      if (item is! Function && item is! Future) {
        return mismatchDescription.add(' not a Function or Future');
      }
  
      if (_matcher == null ||  matchState.state == null) {
        return mismatchDescription.add(' did not throw any exception');
      }
  
  
negative.code:     return _matcher.describe(description);
    }
  
    Description describeMismatch(item, Description mismatchDescription, Map matchState,
                                 bool verbose) {
      return _matcher.describeMismatch(item, mismatchDescription, matchState, verbose);
    }
  