from machine import Pin
import time 

led_piny = [15, 16, 17, 18]
ledky = [Pin(p, Pin.OUT) for p in led_piny]

def vse_vypni():
    for led in ledky:
        led.off()

while True:
    for led in ledky:
        vse_vypni()
        led.on()
        time.sleep(0.1)

    for led in reversed(ledky):
        vse_vypni()
        led.on()
        time.sleep(0.1)