code: def run_loop(leds=all_leds):
      
      print('Loop started.\nPress Ctrl+C to break out of the loop.')
      while 1:
          try:
              if switch():
                  [led.on() for led in leds]
              else:
                  [led.off() for led in leds]
          except OSError: # VCPInterrupt # Ctrl+C in interpreter mode.
              break
docs: Start the loop.
  
      :param `leds`: Which LEDs to light up upon switch press.
      :type `leds`: sequence of LED objects