from machine import Pin
from time import sleep

led = Pin (23, Pin.OUT)
led2 = Pin(21, Pin.OUT)
led3 = Pin(4, Pin.OUT)


while True:
    led.value(1)
    sleep(1)
    led.value(0)
    sleep(1)
    led2.value(1)
    sleep(1)
    led2.value(0)
    sleep(1)
    led3.value(1)
    sleep(1)
    led3.value(0)
    sleep(1)