import RPi.GPIO as GPIO ## Import GPIO Library

import time ## Import 'time' library (for 'sleep')

pin = 7 ## We're working with pin 7

GPIO.setmode(GPIO.BOARD) ## Use BOARD pin numbering

## You can use BCM 4 if you prefer

GPIO.setup(pin, GPIO.OUT) ## Set pin 7 to OUTPUT

for i in range (0, 20): ## Repeat 20 times

GPIO.output(pin, GPIO.HIGH) ## Turn on GPIO pin (HIGH)

time.sleep(1) ## Wait 1 second

GPIO.output(pin, GPIO.LOW) ## Turn off GPIO pin (LOW)

time.sleep(1) ## Wait 1 second

GPIO.cleanup()