def test_iter(self):
        prio_set_list = event._PrioritizedSetList()
        objs = [(i,) for i in range(5)]
        for i, obj in enumerate(objs):
            prio_set_list.add(-i, obj)

        for i, set_ in enumerate(prio_set_list):
            assert set_ == (-i, {objs[i]})
def voltage(title, pos, voltage, ax=0):
    """plot voltage vs. position"""
    if ax == 0:
        ax = plt.gca()
    ax.set_title('{} / V'.format(title))
    ax.grid(True)
    ax.plot(pos, voltage)