from machine import Pin
from utime import sleep
yellow=Pin(8, Pin.OUT)
green=Pin(11, Pin.OUT)
red=Pin(15, Pin.OUT)

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

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