anchor.diff:    V? operator [](Object? key);
     void operator []=(K key, V value);
   
  +  void addAll(Map<K, V> other);
     Map<RK, RV> cast<RK, RV>();
     bool containsKey(Object? key);
  +  void forEach(void action(K key, V value));
  +  V putIfAbsent(K key, V ifAbsent());
   }
   
   class Null extends Object {
  
positive.code:   }
  }
  
  abstract class LinkedHashMap<K, V> implements Map<K, V> {
    external factory LinkedHashMap(
        {bool Function(K, K)? equals,
  
negative.code:   const JsonCodec();
    String encode(Object? value, {Object? toEncodable(dynamic object)?}) => '';
  }
  
  abstract class StringConversionSink { }
  
  abstract class StringConversionSinkMixin implements StringConversionSink { }
  ''',
      )
    ],
  