async def METHOD_NAME():
    app = ExampleApp()
    async with app.run_test():
        container = app.query_one(Vertical)
        # 6 labels in total, with 5 of them inside the container.
        assert len(app.query(Label)) == 6
        assert len(container.children) == 5
        await container.remove_children()
        # The labels inside the container are gone, and the 1 outside remains.
        assert len(app.query(Label)) == 1
        assert len(container.children) == 0