from machine import Pin
from time import sleep

led_pins = [2, 4, 5, 18, 19]

leds = []
for pin in led_pins:
    leds.append(Pin(pin, Pin.OUT))

urutan = [0, 1, 2, 3, 4, 3, 2, 1, 0]

while True:
    for i in urutan:
        leds[i].on()
        sleep(0.25)
        leds[i].off()