#!/usr/bin/python

from time import sleep

import RPi.GPIO as GPIO

yellowLed = 15
redLed = 17
greenLed = 18

sleepTime = 0.25

try:
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(yellowLed, GPIO.OUT)
    GPIO.setup(redLed, GPIO.OUT)
    GPIO.setup(greenLed, GPIO.OUT)

    while True:
        GPIO.output(yellowLed, 1)
        GPIO.output(redLed, 0)
        GPIO.output(greenLed, 0)
        sleep(sleepTime)
        GPIO.output(yellowLed, 0)
        GPIO.output(redLed, 1)
        GPIO.output(greenLed, 0)
        sleep(sleepTime)
        GPIO.output(yellowLed, 0)
        GPIO.output(redLed, 0)
        GPIO.output(greenLed, 1)
        sleep(sleepTime)
except KeyboardInterrupt:
    GPIO.output(yellowLed, 0)
    GPIO.output(redLed, 0)
    GPIO.output(greenLed, 0)
finally:
    GPIO.cleanup()