Python （利用遞歸）科赫雪花的繪製

import turtle
def koch(size, n):
    if n == 0:
        turtle.fd(size)
    else:
        for angle in [0, 60, -120, 60]:
            turtle.left(angle)
            koch(size/3, n-1)
def main():
    turtle.setup(800,800)
    turtle.penup()
    turtle.goto(-300, -50)
    turtle.pendown()
    turtle.pensize(2)
    turtle.color('blue')
    level = 3
    koch(600, level)
    turtle.right(120)
    koch(600, level)
    turtle.right(120)
    koch(600, level)
    turtle.hideturtle()
    turtle.done()
main()