def METHOD_NAME():
    """
    write to cahce an read back
    no uncertainty
    """
    # create a cache object:
    c = cache.ElementCache()
    # create a spill_container to save:
    sc = sample_sc_release(num_elements=10, start_pos=(3.14, 2.72, 1.2))
    # add a timestamp:
    sc.current_time_stamp = dt
    # put it in a SpillContainerPair
    scp = SpillContainerPairData(sc)
    # make a copy of positons for later testing
    pos0 = sc['positions'].copy()
    c.save_timestep(0, scp)
    # change things...
    sc['positions'] += 1.1
    pos1 = sc['positions'].copy()
    # change time stamp
    sc.current_time_stamp = dt + tdelta
    c.save_timestep(1, scp)
    # change things...
    sc['positions'] *= 1.1
    pos2 = sc['positions'].copy()
    # change time stamp
    sc.current_time_stamp = dt + tdelta * 2
    # save it:
    c.save_timestep(2, scp)
    # read them back
    sc2 = c.load_timestep(2)
    assert np.array_equal(sc2._spill_container['positions'], pos2)
    assert sc2._spill_container.current_time_stamp == dt + tdelta * 2
    sc0 = c.load_timestep(0)
    assert np.array_equal(sc0._spill_container['positions'], pos0)
    assert sc0._spill_container.current_time_stamp == dt
    sc1 = c.load_timestep(1)
    assert np.array_equal(sc1._spill_container['positions'], pos1)
    assert sc1._spill_container.current_time_stamp == dt + tdelta
    sc2 = c.load_timestep(2)
    assert np.array_equal(sc2._spill_container['positions'], pos2)
    assert sc2._spill_container.current_time_stamp == dt + tdelta * 2