from machine import Pin
import time
led1= Pin(2,Pin.OUT)
led2= Pin(3,Pin.OUT)
led3= Pin(4,Pin.OUT)
while True:
    led1.toggle()
    time.sleep(1)
    led1.toggle()
    led2.toggle()
    time.sleep(1)
    led2.toggle()
    led3.toggle()
    time.sleep(1)
    led3.toggle()