(defun b ()
  (pinmode 13 :output)
  (digitalwrite 13 nil)
  (delay 500)
  (digitalwrite 13 t)
  (delay 200)
  (digitalwrite 13 nil)
  (delay 500)
  (digitalwrite 13 t)
  (delay 200)
  (digitalwrite 13 nil)
  (delay 500)
  (digitalwrite 13 t)
  (delay 200)
  (digitalwrite 13 nil)
  (delay 500)
  (digitalwrite 13 t)
  (delay 200))
(b)