如何用Python画一颗小树？

def tree(plist,l,a,f):

    if l>5:

        lst=[]

        for p in plist:

            p.forward(l)

            q=p.clone()

            p.left(a)

            q.right(a)

            lst.append(p)

            lst.append(q)

        tree(lst,l*f,a,f)

def main():

    p=Turtle()

    p.color('green')

    p.pensize(11)

    p.hideturtle()

    p.speed(4)

    p.left(90)

    p.penup()

    p.goto(0,-100)

    p.pendown()

    t=tree([p],110,65,0.6375)

main()