from machine import Pin
import time

led1 = Pin(19,Pin.OUT)
led2 = Pin(5,Pin.OUT)
led3 = Pin(4,Pin.OUT)
led4 = Pin(2,Pin.OUT)

while True:
  led1.on()
  led2.on()
  led3.on()
  led4.on()
  time.sleep(0.5)
  led1.off()
  led2.off()
  led3.off()
  led4.off()
  time.sleep(0.5)