from machine import Pin
from time import sleep


led_g = Pin( 15, Pin.OUT)
led_y = Pin( 2, Pin.OUT)
led_r = Pin( 4, Pin.OUT)

while True:
  led_g.value(1) 
  led_y.value(0)
  led_r.value(0)
  sleep(3)
 
  led_g.value(0)
  led_y.value(1)
  led_r.value(0)
  sleep (1)

  led_g.value(0)
  led_y.value(0)
  led_r.value(1) 
  sleep(4)