case class Book( title :String, author :String, numPages :Int, isCopyrighted :Boolean )


// example of the data:
var cih = Book( "The Cat", "Seuss", 37, false )


def enbiggen( original :Book ) :Book = 
  Book( original.title, original.author, original.numPages * 2, original.isCopyrighted )


def derive( original :Book, newAuthor :String, newNumPages :Int ) :Book = {
    Book( "Son of " + original.title, 
           original.author + " & " + newAuthor,
           original.numPages + newNumPages,
           original.isCopyrighted )
    }

assert( enbiggen(cih).equals( Book( "The Cat", "Seuss", 74, false ) ) )