scala>
     |     val queueOrange: Queue[Orange] = new Queue[Orange](Nil, Nil)
queueOrange: Queue[Orange] = Queue@41488b16

scala>     queueOrange.enqueue(new Apple())
res4: Queue[Fruit] = Queue@3cfdd820

scala>     queueOrange.enqueue(new Orange())
res5: Queue[Orange] = Queue@4f4c4b1a

scala>     queueOrange.enqueue(new Fruit("PineApple"))
res6: Queue[Fruit] = Queue@1787bc24

scala>
     |     val queueFruit: Queue[Fruit] = queueOrange
queueFruit: Queue[Fruit] = Queue@41488b16

scala>     queueFruit.enqueue(new Orange())
res8: Queue[Fruit] = Queue@5b7a8434

scala>     queueFruit.enqueue(new Apple())
res9: Queue[Fruit] = Queue@6e005dc9

scala>     queueFruit.enqueue(new Fruit("Pineapple"))
res10: Queue[Fruit] = Queue@35645047