)
;  (define shutdown-sender flush-output)
  )
 (bigloo
  (define (open-tcp-connection host port-number)
    (let ((sock (make-client-socket host port-number)))
      (cons (socket-input sock) (socket-output sock))))
  ; flush-output-port is built-in
  (define shutdown-sender close-output-port)
  )
 ((or plt chicken)
  (define (open-tcp-connection host port-number)
    (call-with-values
     (lambda () (tcp-connect host port-number))
     (lambda (input-port output-port)
       (cons input-port output-port)