(define (point x y)
  (define (self m)
    (cond ((eq? m 'getx) (lambda () x))
          ((eq? m 'gety) (lambda () y))
          ((eq? m 'type) (lambda () 'point))
          ((eq? m 'setx!) (lambda (nx) (set! x nx)))
          ((eq? m 'sety!) (lambda (ny) (set! y ny)))
          ((eq? m 'info) (lambda () (list 'point x y)))
          ((eq? m 'add) (lambda (p)
                          (let ((px ((p 'getx)))
                                (py ((p 'gety))))
                            (point (+ x px) (+ y py)))))
          ((eq? m 'sub) (lambda (p)
                          (let ((px ((p 'getx)))
                                (py ((p 'gety))))
                            (point (- x px) (- y py)))))
          (else (lambda () (display (string-append "Message not understood: " (symbol->string m) "\n"))))))
  self)

(define (send obj . args)
  (if (procedure? obj)
      (if (= (length args) 1)
          ((obj (car args)))
          ((obj (car args)) (car (cdr args))))  ; Extracting the second argument
      (display (string-append "Inappropriate receiver object: " (symbol->string obj) "\n"))))

(define p1 (point 1 2))
(define p2 (point 3 4))
(send p1 'getx) ; 1
(send p1 'gety) ; 2
(send p2 'getx) ; 3
(send p2 'gety) ; 4
(define p (send p1 'add p2))
(send p 'info) ; (point 4 6)
(send 'not-a-point 'info) ; should display "Inappropriate receiver object"
(send p 'foo) ; should display "Message not understood"
(send p 'bar 2) ; should display "Message not understood"
(send p1 'setx! 5)
(send p1 'getx) ; returns 5