Python精灵模块的heading朝向指令

from sprites import Sprite,Screen

screen = Screen()
screen.xy_grid()

cat = Sprite(3)
bug = Sprite()
while True:
    bug.clear()
    bug.gotorandom()
    bug.heading((100,100))  # 角色朝向坐标(100,100)
    bug.draw_line((100,100),bug.pos())
    bug.wait(1)
    bug.heading(cat)
    bug.wait(1)
    bug.draw_line(cat.pos(),bug.pos())
    bug.wait(1)