主题：臭老头，来学python画画了！！！

import turtle as tu

roo = tu.Turtle()  # 创建对象
wn = tu.Screen()  # 屏幕对象
wn.bgcolor("black")  # 屏幕背景
wn.title("分形树")
roo.left(90)  # 移动
roo.speed(20)  # 速度


def draw(l):  # 以长度'l'作为参数的递归函数
    if l < 10:
        return
    else:
        roo.pensize(2)  # 设置画笔大小
        roo.pencolor("yellow")  # 画笔颜色
        roo.forward(l)  # 朝向
        roo.left(30)  # 移动
        draw(3 * l / 4)  # 绘制
        roo.right(60)  # 移动
        draw(3 * l / 4)  # 绘制
        roo.left(30)  # 移动
        roo.pensize(2)
        roo.backward(l)  # 返回初始位置


draw(20)  # 绘制20次

roo.right(90)
roo.speed(2000)


# recursion
def draw(l):
    if (l < 10):
        return
    else:
        roo.pensize(2)
        roo.pencolor("magenta")  # magenta
        roo.forward(l)
        roo.left(30)
        draw(3 * l / 4)
        roo.right(60)
        draw(3 * l / 4)
        roo.left(30)
        roo.pensize(2)
        roo.backward(l)


draw(20)

roo.left(270)
roo.speed(2000)


# recursion
def draw(l):
    if (l < 10):
        return
    else:
        roo.pensize(2)
        roo.pencolor("red")  # red
        roo.forward(l)
        roo.left(30)
        draw(3 * l / 4)
        roo.right(60)
        draw(3 * l / 4)
        roo.left(30)
        roo.pensize(2)
        roo.backward(l)


draw(20)

roo.right(90)
roo.speed(2000)


# recursion
def draw(l):
    if (l < 10):
        return
    else:
        roo.pensize(2)
        roo.pencolor('#FFF8DC')  # white
        roo.forward(l)
        roo.left(30)
        draw(3 * l / 4)
        roo.right(60)
        draw(3 * l / 4)
        roo.left(30)
        roo.pensize(2)
        roo.backward(l)


draw(20)


########################################################

def draw(l):
    if (l < 10):
        return
    else:

        roo.pensize(3)
        roo.pencolor("lightgreen")  # lightgreen
        roo.forward(l)
        roo.left(30)
        draw(4 * l / 5)
        roo.right(60)
        draw(4 * l / 5)
        roo.left(30)
        roo.pensize(3)
        roo.backward(l)


draw(40)

roo.right(90)
roo.speed(2000)


# recursion
def draw(l):
    if (l < 10):
        return
    else:
        roo.pensize(3)
        roo.pencolor("red")  # red
        roo.forward(l)
        roo.left(30)
        draw(4 * l / 5)
        roo.right(60)
        draw(4 * l / 5)
        roo.left(30)
        roo.pensize(3)
        roo.backward(l)


draw(40)

roo.left(270)
roo.speed(2000)


# recursion
def draw(l):
    if (l < 10):
        return
    else:
        roo.pensize(3)
        roo.pencolor("yellow")  # yellow
        roo.forward(l)
        roo.left(30)
        draw(4 * l / 5)
        roo.right(60)
        draw(4 * l / 5)
        roo.left(30)
        roo.pensize(3)
        roo.backward(l)


draw(40)

roo.right(90)
roo.speed(2000)


# recursion
def draw(l):
    if (l < 10):
        return
    else:
        roo.pensize(3)
        roo.pencolor('#FFF8DC')  # white
        roo.forward(l)
        roo.left(30)
        draw(4 * l / 5)
        roo.right(60)
        draw(4 * l / 5)
        roo.left(30)
        roo.pensize(3)
        roo.backward(l)


draw(40)

def draw(l):
    if (l < 10):
        return
    else:

        roo.pensize(2)
        roo.pencolor("cyan")  # cyan
        roo.forward(l)
        roo.left(30)
        draw(6 * l / 7)
        roo.right(60)
        draw(6 * l / 7)
        roo.left(30)
        roo.pensize(2)
        roo.backward(l)


draw(60)

roo.right(90)
roo.speed(2000)


# recursion
def draw(l):
    if (l < 10):
        return
    else:
        roo.pensize(2)
        roo.pencolor("yellow")  # yellow
        roo.forward(l)
        roo.left(30)
        draw(6 * l / 7)
        roo.right(60)
        draw(6 * l / 7)
        roo.left(30)
        roo.pensize(2)
        roo.backward(l)


draw(60)

roo.left(270)
roo.speed(2000)


# recursion
def draw(l):
    if (l < 10):
        return
    else:
        roo.pensize(2)
        roo.pencolor("magenta")  # magenta
        roo.forward(l)
        roo.left(30)
        draw(6 * l / 7)
        roo.right(60)
        draw(6 * l / 7)
        roo.left(30)
        roo.pensize(2)
        roo.backward(l)


draw(60)

roo.right(90)
roo.speed(2000)


# recursion
def draw(l):
    if (l < 10):
        return
    else:
        roo.pensize(2)
        roo.pencolor('#FFF8DC')  # white
        roo.forward(l)
        roo.left(30)
        draw(6 * l / 7)
        roo.right(60)
        draw(6 * l / 7)
        roo.left(30)
        roo.pensize(2)
        roo.backward(l)


draw(60)
wn.exitonclick()