from machine import Pin
import time

led1 = Pin(2,Pin.OUT)
led2 = Pin(4,Pin.OUT)
led3 = Pin(16,Pin.OUT)

while True:
    led1.value(1)
    led2.value(0)
    led3.value(0)
    print("RED is ON")
    time.sleep(3)


    led1.value(0)
    led2.value(1)
    led3.value(0)
    print("Yellow is ON")
    time.sleep(3)

    led1.value(0)
    led2.value(0)
    led3.value(1)
    print("GREEN is ON")
    time.sleep(3)