def test_add(self):
        prio_set_list = event._PrioritizedSetList()
        objs = [(i,) for i in range(5)]

        prio_set_list.add(0, objs[0])
        assert prio_set_list.list == [(0, {objs[0]})]

        prio_set_list.add(0, objs[1])
        assert prio_set_list.list == [(0, {objs[0], objs[1]})]

        prio_set_list.add(10, objs[2])
        assert prio_set_list.list == [(10, {objs[2]}),
                                      (0,  {objs[0], objs[1]})]

        prio_set_list.add(-10, objs[3])
        assert prio_set_list.list == [( 10, {objs[2]}),           # noqa: E201
                                      (  0, {objs[0], objs[1]}),  # noqa: E201
                                      (-10, {objs[3]})]
        prio_set_list.add(-1, objs[4])
        assert prio_set_list.list == [( 10, {objs[2]}),           # noqa: E201
                                      (  0, {objs[0], objs[1]}),  # noqa: E201
                                      ( -1, {objs[4]}),           # noqa: E201
                                      (-10, {objs[3]})]
def loss_density(isa, subreg=[], ax=0):
    """plot loss density of NC/I7/ISA7 model
    Args:
      isa: Isa7/NC object
    """
    if subreg:
        if isinstance(subreg, list):
            sr = subreg
        else:
            sr = [subreg]
        elements = [e for s in sr for sre in isa.get_subregion(s).elements()
                    for e in sre]
    else:
        elements = [e for e in isa.elements]

    lossd = np.array([e.loss_density*1e-3 for e in elements])
    _contour(ax, 'Loss Density kW/m³', elements, lossd)