from machine import Pin
from time import sleep

red=Pin(8,Pin.OUT)
yellow=Pin(11,Pin.OUT)
green=Pin(15,Pin.OUT)

while True:
    red.on()
    sleep(1.4)
    red.off()
    sleep(1.4)

    yellow.on()
    sleep(1.4)
    yellow.off()
    sleep(1.4)

    green.on()
    sleep(1.4)
    green.off()
    sleep(1.4)