def ghost():
    global offset
    if pix_col == 255:
        light.set_pixel_color(pic_col, 0x0000ff)
        light.set_pixel_color(rng - 1, 0x000000)
        offset = 1
    else:
        if offset == 0:
            light.set_pixel_color(rng - 1, 0x000000)
            offset = 0
        offset = 0
    pause(100)

def on_button_a_click():
    global rng, pix_col, pic_col, value
    rng += 1
    pix_col = light.pixel_color(rng)
    pic_col = rng
    if rng > 9:
        light.set_pixel_color(rng - 1, 0x000000)
        rng = 0
        pix_col = light.pixel_color(rng)
        pic_col = rng
        ghost()
    light.set_pixel_color(rng, 0xff0000)
    ghost()
    value = 1 / (1 / rng) * 10 + dly * 1
input.button_a.on_event(ButtonEvent.CLICK, on_button_a_click)

def on_button_b_click():
    global mode
    light.clear()
    pause(100)
    mode += 1
    if mode > 1:
        mode = 0
        light.set_pixel_color(rng, 0xff0000)
        light.set_pixel_color(dly, 0x000000)
        pause(100)
input.button_b.on_event(ButtonEvent.CLICK, on_button_b_click)

mode = 0
value = 0
offset = 0
pic_col = 0
pix_col = 0
rng = 0
dly = 0
dly = 0
rng = 0
light.set_brightness(255)
light.set_pixel_color(0, 0xff0000)
pins.A1.digital_write(False)
list2 = [Colors.RED,
    Colors.ORANGE,
    Colors.YELLOW,
    Colors.GREEN,
    Colors.BLUE,
    Colors.INDIGO,
    Colors.VIOLET,
    Colors.PURPLE,
    Colors.WHITE]

def on_forever():
    if mode == 1 and value > 0:
        light.set_all(0xffffff)
        pause(value)
        light.set_all(0x000000)
    else:
        pins.A1.digital_write(True)
        pause(value)
        pins.A1.digital_write(False)
forever(on_forever)