import RPi.GPIO as GPIO
import time

# blinking function
def blink(pin):
        GPIO.output(pin,GPIO.HIGH)
        time.sleep(1)
        GPIO.output(pin,GPIO.LOW)
        time.sleep(1)
        return

# to use Raspberry Pi board pin numbers
GPIO.setmode(GPIO.BOARD)

# set up GPIO output channel
GPIO.setup(21, GPIO.OUT)

# blink GPIO21 50 times
for i in range(0,50):
        blink(11)

GPIO.cleanup() 

Create led.py