Currently, Madrigal can place an order no matter how little gold and silver is in their purse – even if there is none. This is an unsustainable business model for Taernyl’s Folly. In this challenge you will correct that.
Update the code for performPurchase to determine whether the purchase can be performed.
If it cannot, no money should change hands, and instead of the message "Madrigal buys a Dragon’s Breath (shandy) for 5.91", a message from the bartender explaining that the customer is short on gold should be printed.
To simulate multiple orders, call performPurchase several times in the placeOrder function.