async def METHOD_NAME(marker_trackerstore: TrackerStore):
    """Tests loading trackers using 'first_n' strategy."""
    loader = MarkerTrackerLoader(marker_trackerstore, STRATEGY_FIRST_N, 3)
    result = [tracker async for tracker in loader.load()]
    assert len(result) == 3
    for item in result:
        assert await marker_trackerstore.exists(item.sender_id)