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 make_grayscale(img):
    ret = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    return ret