@Model
            void createContainer(Container c) {
                c.items = []
                c.widgets = []
                c.rawWidgets = []
            }

            @Mutate
            void addItems(Container c) {
                c.items.add new Widget()
                c.widgets.add new Widget()
                c.rawWidgets.add new Widget()
            }

            @Mutate

type MapType interface {
	NewMap() Map
}

type Map interface {
	AddItem()
	DelItem()
	Len() int
	GetItem()
	RangeAll()
}

func stressMapType(mt MapType, done func()) {
	defer done()
	m := mt.NewMap()
	for m.Len() < 10000 {
		Println("map at ", m.Len())
		if m.Len()%100 == 0 {
			runtime.Gosched()
		}
		m.AddItem()
		m.AddItem()
		m.DelItem()
		var wg sync.WaitGroup
		const numGets = 10