from machine import Pin
import time 
red_led=Pin(2,Pin.OUT)
yellow_led=Pin(3,Pin.OUT)
green_led=Pin(4,Pin.OUT)



while True:
    red_led.value(1)
    yellow_led.value(0)
    green_led.value(0)
    time.sleep(2)
      
    red_led.value(0)
    yellow_led.value(1)
    green_led.value(0)
    time.sleep(2)
    
    red_led.value(0)
    yellow_led.value(0)
    green_led.value(1)
    time.sleep(2)