Python雪花

import turtle
def show(n,size):
    if n==1:
        turtle.fd(size)
    else:
        for angle in [0,60,-120,60]:
            turtle.left(angle)
            show(n-1,size/3)
turtle.setup(800,800)
turtle.penup()
turtle.goto(-200,100)
turtle.pendown()
turtle.pensize(2)
level=3
show(level,400)
turtle.right(120)
show(level,400)
turtle.right(120)
show(level,400)
turtle.right(120)
turtle.done()#窗口保持