You may find yourself writing code that refers to
variables and functions in base classes. This is
particularly true if your derived class is a refinement
or specialisation of code in your base class.
Instead of using the literal name of the base class in your
code, you should be using the special name
parent, which refers to the name of your
base class as given in the extends
declaration of your class. By doing this, you avoid using the
name of your base class in more than one place. Should
your inheritance tree change during implementation, the
change is easily made by simply changing the
extends declaration of your class.
