def METHOD_NAME():
    f = db.get_timestep("test_tipsy/tiny.000640").load()
    f2 = db.get_timestep("test_tipsy/tiny.000640").load()
    h = db.get_halo("test_tipsy/tiny.000640/1").load()
    h_tracker = db.get_halo("test_tipsy/tiny.000640/tracker_1").load()
    assert id(f)==id(f2)
    assert id(h.ancestor)==id(f)
    assert id(h_tracker.ancestor)==id(f)
    old_id = id(f)
    del f, f2, h, h_tracker
    gc.collect()
    f3 = db.get_timestep("test_tipsy/tiny.000640").load()
    assert id(f3)!=old_id