Assume the existence of a Building class with a constructor that accepts two parameters: a reference to an Address object representing the building's address, and an int for the square footage of the building. Assume a subclass ApartmentBuilding has been defined with a single int instance variable, totalUnits. Write a constructor for ApartmentBuilding that accepts three parameters: an Address and an int to be passed up to the Building constructor, and an int used to initialize the totalUnits instance variable.