As a teaching/learning aid, here is a simple bit of code to cycle through the LEDs / Outputs on a Raspberry Pi with Piface attachment board.

piface_cycle_leds.py

import piface.pfio
import time
import sys

def main(argv):
        piface.pfio.init()

        cnt = 0
        loop = 0

        while loop < 10:
                for cnt in range(0, 8):
                        led = piface.pfio.LED(cnt)
                        led.turn_on()
                        time.sleep(1)
                        led.turn_off()

                loop = loop+1



if __name__ == "__main__":
    sys.exit(main(sys.argv))