A subclass can decide to override an inherited method if the inherited
method is not adequate.
For example, the generic display method in the Item class
cannot know how to label the attributes of an Oxford shirt since such these
attributes are in the OxfordShirt class.
So OxfordShirt could decide to implement its own version of
display.
The Chino class could do the same thing.
Since the display method does
different things depending on the type
of object involved, it is polymorphic.