anchor.diff:    Map<K, Iterable<V>> asMap();
   
     /**
  -   * Returns a view of this multimap as a map.
  -   *
  -   * DEPRECATED: this method is replaced with `asMap`.
  -   */
  -  @Deprecated('Will be removed in 0.22.0')
  -  Map<K, Iterable<V>> toMap();
  -
  -  /**
      * The number of keys in the multimap.
      */
     int get length;
  
positive.code:   Set<V> operator [](Object key) => super[key];
    Set<V> removeAll(Object key) => super.removeAll(key);
    Map<K, Set<V>> asMap() => new _WrappedMap<K, V, Set<V>>(this);
    @Deprecated('Will be removed in 0.22.0')
    Map<K, Set<V>> toMap() => asMap();
  }
  
  /**
  
negative.code:   List<V> operator [](Object key) => super[key];
    List<V> removeAll(Object key) => super.removeAll(key);
    Map<K, List<V>> asMap() => new _WrappedMap<K, V, List<V>>(this);
  }
  
  /**
  