import RPi.GPIO as GPIO
import time

channel = 21

# GPIO setup
GPIO.setmode(GPIO.BCM)
GPIO.setup(channel, GPIO.OUT)


def light_on(pin):
    GPIO.output(pin, GPIO.HIGH)  # Turn light on

def light_off(pin):
    GPIO.output(pin, GPIO.LOW)  # Turn light off

if __name__ == '__main__':
    try:
        light_off(channel)
        time.sleep(1)
        light_on(channel)
        time.sleep(1)
        GPIO.cleanup()
    except KeyboardInterrupt:
        GPIO.cleanup()