new_contents: '''
  LED
  Turns on and off (blink) an on-board LED with decremental intervals.
  
  Pluto has collect some number of Arduino boards with on-board LED attached to pin 13. For these boards, Pluto can recognize automatically through the use of the board's class. If unsure, consult the doc at http://arduino.cc and use general Board class, then supply the pin number as the argument to led callable.
  
  This example code is in the public domain.
  
  modified June 22, 2015
  by Joe Chasinga
  '''
  
  #!/usr/bin/env python
  
  import sys, os, math
  sys.path.append('../pluto')
  
  from pluto import *
  import time
  
  board = Board()
  
  def blink():
      angle = 0
      
      while True:
          t = abs(math.sin(angle))
          
          board.led(13).on()
          time.sleep(t/12)
          board.led(13).off()
          time.sleep(t/12)
          
          angle = angle + 0.02
  
  if __name__ == '__main__':
      blink()
      
  
subject: Add example