text: 
  var balanceManager = require('./balanceManager');
  var changeHandler = require('./changeHandler');
  var productInventory = require('./productInventory');
  
  module.exports = {
    insertCoin: function(coinType){
      var value = changeHandler.getAmount(coinType);
      balanceManager.increaseBalance(value);
    },
    vendProduct: function(productId){
      var product = productInventory.getProduct(productId);
      balanceManager.decreaseBalance(product.price);
      return product;
    },
    getProducts: function(){
      return productInventory.getProducts();
    },
    releaseChange: function(){
      var balance = balanceManager.getBalance();
      balanceManager.decreaseBalance(balance);
      return changeHandler.convertToChange(balance);
    }
  };
  