import time
from machine import Pin 
from time import sleep
time.sleep(0.1) # Wait for USB to become ready
led1=Pin(2,Pin.OUT)
led2=Pin(5,Pin.OUT)
led3=Pin(9,Pin.OUT)
led4=Pin(12,Pin.OUT)
while True:
   led1.value(0)
   led2.value(0)
   led3.value(0)
   led4.value(0)
   sleep(.5)
   led1.value(0)
   led2.value(0)
   led3.value(1)
   led4.value(0)
   sleep(.5)
   led1.value(0)
   led2.value(0)
   led3.value(0)
   led4.value(0)
   sleep(.5)