#!/usr/bin/env python3

from time import sleep
try:
    import RPi.GPIO as GPIO
except RuntimeError:
    print("Error importing RPi.GPIO! Run this script as root.")
    exit(1)

LED_RED = 17
LED_GREEN = 18

def setup():
    # Run GPIO with PI pin numbers.
    GPIO.setmode(GPIO.BCM)
    # Set outputs fpr led pins
    GPIO.setup(LED_RED, GPIO.OUT)
    GPIO.setup(LED_GREEN, GPIO.OUT)

def main():
    setup()
    try:
        while True:
            GPIO.output(LED_RED, GPIO.HIGH)
            GPIO.output(LED_GREEn, GPIO.LOW)
            sleep(1)
            GPIO.output(LED_RED, GPIO.LOW)
            GPIO.output(LED_GREEn, GPIO.HIGH)
            sleep(1)
    except KeyboardInterrupt:
        GPIO.cleanup()


if __name__ == "__main__":
    main()