colours.add(Colour.BLUE);
colours.add(Colour.RED);
colours.add(Colour.GREEN);
List pets = new ArrayList();
pets.add(new Pet("Rudiger"));
pets.add(new Pet("Spot"));
pets.add(new Pet("Fluffy"));
pets.add(new Pet("Mufty"));
Set someObjects = new HashSet();
someObjects.add(new ItemPet("PET1"));
someObjects.add(new ItemPet("PET2"));