ViewModel {
	
	var state: State

	init {
		db.foosObservable()
			.map { foos -> foos.map { Item(it.title, expandedOrCollapsed = false) }}
			.subscribe {
				sync(state.items, it)
			}
	}

	private fun sync(currentItems: List<Item>, newItems: List<Item>) {
		// update the titles, but preserve the expandedOrCollapsed of current items
	}

	data class State(val items: List<Item>)

	data class Item(val title: String, val expandedOrCollapsed: Boolean)
}