Python精灵模块的symmetric_points指令

import turtle
from sprites import Screen,symmetric_points,Mouse    

# 一个定点,作为中心对称点
center = (0,0)
cors = [(100,100),(100,50)]
cors2 = symmetric_points(cors,center)
for p1,p2 in zip(cors,cors2):
    turtle.goto(p1);turtle.dot(10,'red');turtle.pd()
    turtle.goto(p2);turtle.dot(10,'blue');turtle.pu()   

turtle.done()