my_tree.py

import turtle

pen = turtle.Turtle()
pen.color('sienna')
pen.speed(0)

# 画布大小
w = turtle.Screen()
w.bgcolor('wheat')      # wheat小麦

# 移动到起点
pen.left(90)
pen.up()
pen.backward(150)    # 后退
pen.down()

def tree(n):
    if n>=40:
        pen.fd(n)
        pen.right(30)
        tree(n-15)
        pen.left(60)
        tree(n-15)
        pen.right(30)
        pen.up()
        pen.backward(n)
        pen.down()
tree(100)



turtle.done()