import time
import machine
from machine import Pin
from time import sleep

Red_led = Pin(0, Pin.OUT)
Yelw_led = Pin(1,Pin.OUT)
Gren_led = Pin(2,Pin.OUT)

while True:
    time.sleep(3)
    Red_led.value(1)
    time.sleep(3)
    Yelw_led.value(1)
    time.sleep(3)
    Red_led.value(0)
    time.sleep(3)
    Gren_led.value(1)
    time.sleep(3)
    Yelw_led.value(0)
    time.sleep(3)
    Yelw_led.value(1)
    time.sleep(3)
    Gren_led.value(0)
    time.sleep(3)
    Red_led.value(1)
    time.sleep(3)
    Yelw_led.value(0)
    time.sleep(3)