python: draw a tree recursively

Python recursive program drawing:

https://python123.io/index/turtles/5e3a9694883dab383425d574

screenshot:

code:

#20200731 程序猿
# python 递归画图
import turtle

SIZE_TREE = 40


def draw_tree(size):
    if size > SIZE_TREE:
         # 给最后的树枝画绿色
        turtle.pendown()
        if size <=50:
            turtle.color('green')
        else:
            turtle.color('brown')
        turtle.forward(size)
        
        # 右边
        turtle.right(20)
        draw_tree(size -5)
        # 左边
        turtle.left(40)
        draw_tree(size -5)

        # 抬笔，回到之前的树枝
        turtle.right(20)
        turtle.penup()
        turtle.backward(size)

def main():
    turtle.speed(2)
    turtle.hideturtle()
    turtle.penup()
    # 方向向上
    turtle.left(90)
    turtle.backward(100)
    turtle.showturtle()
    # 画笔隐形
    # 画笔有效
    turtle.pendown()
    turtle.pensize(2)
    turtle.color('brown')
    # 给出根的长度
    draw_tree(60)
    
main()