Plan the logic for a program that continuously prompts a user for a customer number until an appropriate sentinel value is entered. Also prompt each user for the stock number of an item being ordered and the quantity ordered. If the customer number is not between $1000$ and $7999$ inclusive, and is not the sentinel$,$ continue to prompt until a valid customer number is entered. If the stock number of the item is not between $201$ and $850$ inclusive, continue to prompt for the stock number. Pass the stock number to a method that a colleague at your organization has written; the method$$s signature is num get Price$($num stock Number$).$ The get Price$()$ method accepts a stock number and returns the price of the item. Multiply the price by the quantity ordered, giving the total due. Pass the customer number and the calculated price to a prewritten method whose signature is void displayBill$($num custNum, num price$).$ This method determines the customer$$s name and address by using the customer ID number, and calculates the final bill, including tax, using the price. Organize your program using as many methods as you think are appropriate. You do not need to write the getPrice$()$ and displayBill$()$ methods$$assume they have already been written.