from machine import pin
from time import sleep_ms

led1 = pin(18, pin.OUT)
led2 = pin(19, pin.OUT)
led3 = pin(20, pin.OUT)
led4 = pin(21, pin.OUT)

while True:
    led1.value(1)
    led2.value(1)
    led3.value(1)
    led4.value(1)
    sleep_ms(200)

    led1.value(0)
    led2.value(0)
    led3.value(0)
    led4.value(0)
    sleep_ms(200)