python - 再帰的システム

Question

Lシステムを使ってPythonでバーンズリーシダを作ろうとしています。しかし、私は自分が望む結果を得ることができません。これが私の最終目標私が手に入れたいもの

しかし、代わりに、コードを実行すると、これが得られます。

これは私が得るものです

これが私のコードです:`

import turtle

def drawLS(aTurtle, instructions, angle, distance):
    stateSaver = []
    print(instructions)
    for cmd in instructions:
        if cmd == 'F':
            aTurtle.forward(distance)
        elif cmd == 'B':
            aTurtle.backward(distance)
        elif cmd == '+':
            aTurtle.right(angle)
        elif cmd == '-':
            aTurtle.left(angle)
        elif cmd == '[':
            pos = aTurtle.position()
            head = aTurtle.heading()
            stateSaver.append((pos, head))
        elif cmd == ']':
            pos, head = stateSaver.pop()
            aTurtle.up()
            aTurtle.setposition(pos)
            aTurtle.setheading(head)
            aTurtle.down()

def applyProduction(axiom, rules, n):
    for i in range(n):
        newString = ""
        for ch in axiom:
            newString = newString + rules.get(ch, ch)
        axiom = newString
    return axiom


def lSystem(axiom,rules,depth,initialPosition,heading,angle,length):
    aTurtle = turtle.Turtle()
    win = turtle.Screen()
    aTurtle.up()
    aTurtle.setposition(initialPosition)
    aTurtle.left(90)
    aTurtle.down()
    aTurtle.setheading(heading)
    aTurtle.speed(0)
    newRules = applyProduction(axiom, rules, depth)
    drawLS(aTurtle, newRules, angle, length)
    win.exitonclick()

myRules={'X':'F+[[X]-X]+X','F':'FF'}
axiom='X'
lSystem(axiom, myRules, 7, (-150,-25), 360, 25, 2)

`