(defun b ()
  (pinmode 7 :output)
  (digitalwrite 7 t)
  (delay 200)
  (digitalwrite 7 nil)
  (delay 500)
  (digitalwrite 7 t)
  (delay 200)
  (digitalwrite 7 nil)
  (delay 500)
  (digitalwrite 7 t)
  (delay 200)
  (digitalwrite 7 nil)
  (delay 500))
(b)