from machine import Pin
import utime

led1 = Pin(0, Pin.OUT)
led2 = Pin(1, Pin.OUT)
led3 = Pin(2, Pin.OUT)

delay = 0.5

while True:
   led1.value(1)
   utime.sleep(0.5)
   led1.value(0)
   utime.sleep(0.5)
   led2.value(1)
   utime.sleep(0.5)
   led2.value(0)
   utime.sleep(0.5)
   led3.value(1)
   utime.sleep(0.5)
   led3.value(0)
   utime.sleep(0.5)