l-system plant

def plant(length, decrease, angle, constant):
    if length > 10:
        tr.width(length / 10)
        tr.forward(length)
        new_length = length * decrease
        if constant > 0:
            new_length *= random.uniform(0.8, 1.1)
        angle_l = angle + random.gauss(0, constant)
        angle_r = angle + random.gauss(0, constant)

        tr.left(angle_l)
        plant(new_length, decrease, angle, constant)
        tr.right(angle_l)

        tr.right(angle_r)
        plant(new_length, decrease, angle, constant)
        tr.left(angle_r)

        tr.backward(length)


tr.penup()
tr.goto(0, -400)
tr.pendown()
tr.left(90)
tr.tracer(30, 0)
plant(150, 0.8, 20, 5)
tr.tracer(True)
tr.exitonclick()