from Arduino import Arduino
import time

board = Arduino('9600',port="/dev/cu.usbserial-FTGZIDCK")  #plugged in via USB, serial com at rate 9600
board.pinMode(13, "OUTPUT")
led_pin = 13

while True:
    board.digitalWrite(led_pin, "LOW")
    print "LOW" # confirm LOW (0)
    time.sleep(1)
    board.digitalWrite(led_pin, "HIGH")
    print "HIGH"  # confirm HIGH (1)
    time.sleep(1)