!7

p {
  L l = ll();
  assertSame("ArrayList", collectionMutex(l), l);
  
  // not so trivial
  // new HashMap map;
  // assertSame("HashMap", collectionMutex(keySet(map)), map);
  
  Map map = caseInsensitiveMap();
  assertSame("caseInsensitiveMap", collectionMutex(printClassName(keySet(map))), map);
  
  print("OK (excluding HashMap)");
}