In this project, you will implement a new class a bag with receipts. This new class similar to an ordinary bag, but the way that items are added and removed is different. Each time an item is added to a bag with receipts, the insert function returns integer called the receipt. Later, when you want to remove an item, you must provide a copy of the receipt as a parameter to the remove function. The remove function removes the item whose receipt has been presented, and also returns a copy of that item through a reference parameter.