l.ObjectCollection({});
    const scopedId1 = new tr.model.ScopedId('ptr', '0x1000');
    const scopedId2 = new tr.model.ScopedId('cc', '0x1000');
    collection.idWasCreated(
        scopedId1, 'cat', 'ptr::object', 10);
    collection.idWasDeleted(
        scopedId1, 'cat', 'ptr::object', 15);
    collection.idWasCreated(
        scopedId2, 'cat', 'cc::object', 10);
    collection.idWasDeleted(
        scopedId2, 'cat', 'cc::object', 15);

    let instance = collection.getObjectInstanceAt(scopedId1, 10);
