anchor.diff:  
   import 'kitchen_sink_interface.dart';
   import 'strict_keys_object.dart';
  +
  +// copied and renamed as private from /lib/src/constants.dart
  +const _generatedLocalVarName = 'val';
  +const _toJsonMapHelperName = 'writeNotNull';
   
   final _isATypeError = const TypeMatcher<TypeError>();
   
  
positive.code:   'dynamicIntMap': const {'key': 'value'},
    'objectDateTimeMap': const {'key': 42},
    'crazyComplex': const [true],
    generatedLocalVarName: const {'key': 42},
    toJsonMapHelperName: 42,
    r'$string': true,
    'simpleObject': 42,
    'strictKeysObject': const {
  
negative.code:   'dynamicIntMap': const {},
    'objectDateTimeMap': const <String, dynamic>{},
    'crazyComplex': const [],
    _generatedLocalVarName: const {},
    _toJsonMapHelperName: null,
    r'$string': null,
    'simpleObject': const {'value': 42},
    'strictKeysObject': const {'value': 10, 'custom_field': 'cool'},
  