For this HW$,$ you will create $3$ python files according to the following description.

Create a class named Retailitem that holds data about an item in a retail store. The class should store the following private data attributes: item description, units in inventory, and price.

P Please define the $3$ data attributes $($class variables$)$ as private attributes and name them as description, inventory, and price.Create a CashRegister class $($complete the starter file$)$ that can be used with the Retailitem class. The CashRegister class has a private data attribute named as items, which is a list object that is used to internally keep a list of Retailitem objects. The class should have the following methods:A A method named purchase$\_$item that accepts a Retailltem object as an argument. Each time the purchase$\_$item method is called, the Retailitem object that is passed as an argument should be added to the list.Demonstrate the CashRegister class in a hw$4.$py program $($complete the starter file$)$ that allows the user to select several items for purchase. When the user is ready to check out, the program should display a list of all the items he or she has selected for purchase, as well as the total price.