def test_order(self):
        assert (event.Priority.PRE_CORE
                > event.Priority.CORE
                > event.Priority.POST_CORE
                > event.Priority.PRE_DEFAULT
                > event.Priority.DEFAULT
                > event.Priority.POST_DEFAULT)
def __init__(self, root, transforms=None):

        super().__init__(root=root)
        self.transforms = transforms

        self._flow_list = []
        self._image_list = []