anchor.diff:        var parser = digit().plus().token();
         expectFailure(parser, '');
         expectFailure(parser, 'a');
  -      var token = parser
  +      Token token = parser
             .parse('123')
             .value;
         expect(token.value, ['1', '2', '3']);
  
positive.code:     });
      test('token() on list', () {
        var parser = any().plus().token();
        var token = parser
            .parse([1, 2, 3])
            .value;
        expect(token.value, [1, 2, 3]);
  
negative.code: }
  
  @deprecated
  typedef void PluggableCompositeParserCallback(CompositeParser self);
  
  @deprecated
  class PluggableCompositeParser extends CompositeParser {
    final PluggableCompositeParserCallback _callback;
  
    PluggableCompositeParser(this._callback) : super();
  
    @override
    void initialize() => _callback(this);
  }
  
  main() {
  