OxfordShirtInfo should override display to make it more
specific to shirts:
The item's price is 49.99
The item's color is Navy blue
The item's neck size is 15
The item's sleeve length is 33
However, it should make use of what ItemInfo can do to avoid
repetitive code.
In our example: ItemInfo::display.
The scope resolution operator disambiguates names that are reused within classes.