Complete the car class by creating an attribute purchase_price (type int) and the method print_info() that outputs the car's information. Ex: if the input is: 2011 18000 2018 where 2011 is the car's model year, 18000 is the purchase price, and 2018 is the current year, then print_info() outputs: car's information: model year: 2011 purchase price: $18000 current value: $5770.