from machine import Pin
from utime import sleep

led_R=Pin(5,Pin.OUT)
led_Y=Pin(11,Pin.OUT)
led_G=Pin(6,Pin.OUT)

while True:
    led_R.high()
    sleep(20)
    led_R.low()

    led_G.high()
    sleep(10)
    led_G.low()

    led_Y.high()
    sleep(2)
    led_Y.low()