效果如下：

代码如下：

from turtle import *from random import *from math import *def tree(n, l):    pd()    t = cos(radians(heading() + 45)) / 8 + 0.25    pencolor(t, t, t)    pensize(n / 4)    forward(l)    if n > 0:        b = random() * 15 + 10        c = random() * 15 + 10        d = l * (random() * 0.35 + 0.6)        right(b)        tree(n - 1, d)        left(b + c)        tree(n - 1, d)        right(c)    else:        right(90)        n = cos(radians(heading() - 45)) / 4 + 0.5        pencolor(n, n, n)        circle(2)        left(90)    pu()    backward(l)bgcolor(0.5, 0.5, 0.5)ht()speed(0)tracer(0, 0)left(90)pu()backward(300)tree(13, 100)done()