Write an invoice class. invoice constructor initializes the class's four data members partnumber // the number of the part being sold partdescription // description of the part being sold quantity // how many of the items are being sold priceperitem // price per item there is a constructor which takes four parameters which are corresponding to the four data members defined above. there are four getters and four setters setpartnumber(std: : string number), setpartdescription(std: : string description), setquantity(int count), if count less than zero then quantity will be set to zero. setpriceperitem(int price), if price < 0 then priceperitem sell be set to zero there is another function getinvoiceamount() which will calculates invoice amount by multiplying quantity x price per item