from turtle import *
from random import *

def tree(n):
    if n >= 0:
        pen.fd(n)
        pen.rt(30)
        tree(n - 10)
        pen.lt(60)
        tree(n - 10)
        pen.rt(30)
        pen.pu()
        pen.bk(n)
        pen.pd()

pen = Pen()
pen.color('sienna')
#pen.ht()
# 画布大小
w = Screen()
w.bgcolor('wheat')      # wheat小麦
# 移动到起点
pen.lt(90)
pen.pu()
pen.bk(150)    # 后退
pen.pd()

tree(50)

done()