// elements are put to front when added (not when accessed)
sclass MRUCache<A, B> extends LinkedHashMap<A, B> {
  int maxSize = 10;

  *() {}
  *(int *maxSize) {}
  
  protected bool removeEldestEntry(Map.Entry eldest) {
    ret size() > maxSize;
  }
  
  O _serialize() {
    ret ll(maxSize, cloneLinkedHashMap(this));
  }
}