from machine import Pin
import time

green=Pin(17,Pin.OUT)
yellow=Pin(14,Pin.OUT)
red=Pin(15,Pin.OUT)

green.off()
yellow.off()
red.off()

while True:
    red.off()
    green.on()
    time.sleep(10)
    green.off()
    yellow.on()
    time.sleep(10)
    yellow.off()
    red.on()
    time.sleep(10)