Call cv.add(),but it doesn't return the correct answer

Here is my code:

import cv2 as cvimport numpy as npx=np.uint8([250])y=np.uint8([10])print("x's shape",x.shape)print("y's shape",y.shape)print(cv.add(x,y))

and after running the code, the result is as follows:

It should be [[255]] for the question.