(require-extension srfi-18)

(define (p note time)
  (display note)
  (display " - ")
  (display "ON!\n")
  (thread-sleep! time)
  (display note)
  (display " - ")
  (display "OFF!\n"))
 
(define (two p1 p2)
  (let ((t1 (make-thread p1))
        (t2 (make-thread p2)))
    (begin
      (thread-start! t1)
      (thread-start! t2)
      (thread-join! t1)
      (thread-join! t2))))

(two (lambda () (p 60 2))
     (lambda () (p 67 3)))