import machine 
import time
#Define the GPIO pins for the traffic light LEDs
RED_LED_PIN = 1 #GP0
YELLOW_LED_PIN = 5 #GP1
GREEN_LED_PIN = 9 #GP2

#Initialize the GPIO pins for the LEDs 
red_led = machine.Pin(RED_LED_PIN, machine.Pin.OUT)
yellow_led = machine.Pin(YELLOW_LED_PIN,machine.Pin.OUT)
green_led = machine.Pin(GREEN_LED_PIN,machine.Pin.OUT)

#Function to turn on the specified LED and turn off the others 
def turn_on_led(led_pin):
    red_led.value(led_pin == RED_LED_PIN)
    yellow_led.value(led_pin == YELLOW_LED_PIN)
    green_led.value(led_pin == GREEN_LED_PIN)

#Traffic light sequence
while True:
    #Red light
    turn_on_led(RED_LED_PIN)
    time.sleep(5) #Red light for 5 seconds

    #Red and yellow lights(transition)
    turn_on_led(YELLOW_LED_PIN)
    time.sleep(2) #Red and yellow lights for 2 seconds

    #Green light 
    turn_on_led(GREEN_LED_PIN)
    time.sleep(5) #Green light for 5 seconds

    #Yellow light
    turn_on_led(YELLOW_LED_PIN)
    time.sleep(2) #Yellow light for 2 seconds