Ex-3.4

(define (make-account balance secret-passwd)
  (define (withdraw amount)
    (if (>= balance amount)
        (begin (set! balance (- balance amount))
               balance)
        "Insufficient funds"))
  (define (deposit amount)
    (set! balance (+ balance amount))
    balance)
  (let ((counter 0))
    (define (dispatch p m)
      (if (eq? p secret-passwd)
          (begin
            (cond 
             ((eq? m 'withdraw) withdraw)
             ((eq? m 'deposit) deposit)
             (else (error "Unknown request -- MAKE-ACCOUNT"
                        m)))
            (set! counter 0))
          (begin
            (set! counter (+ counter 1))
            (if (> counter 7) "Call the cops"
                "Incorrect Password"))))
    dispatch))