from machine import Pin
import time

pins = [17, 18, 19, 20, 21, 22]
leds = [Pin (pin, Pin.OUT) for pin in pins]

while True:
    for led in leds:
        led.value(1)
        time.sleep(1)

    leds.reverse()
    for led in leds:
        led.value(0)
        time.sleep(1)
    leds.reverse()