from machine import Pin
import time
led1 = Pin(15, Pin.OUT)
led2 = Pin(18, Pin.OUT)
led3 = Pin(21, Pin.OUT)
led4 = Pin(22, Pin.OUT)
while True:
    led1.value(1)
    led3.value(1)
    led2.value(0)
    led4.value(0)
    time.sleep(0.5)
    
    led1.value(0)
    led3.value(0)
    led2.value(1)
    led4.value(1)
    time.sleep(0.5)