#lang racket

(require racket/contract)

(struct account (balance))

(provide new-account balance withdraw deposit account)

;; A new, empty account
(define new-account (account 0))

;; Get the current balance
(define (balance acc)
  (account-balance acc))

;; Withdraw funds from an account
(define (withdraw acc amt)
  (account (- (account-balance acc) amt)))

;; Add funds to an account
(define (deposit acc amt)
  (account (+ (account-balance acc) amt)))