Template Method types

Template Method is a behavioral design pattern that defines the skeleton of an algorithm in the superclass but lets subclasses override specific steps of the algorithm without changing its structure:

• abstract 
  Must be implemented by every subclass.
• optional
  Already have some default implementation, but still can be overridden if needed.
• hook 
  Optional step with an empty body. 
  Usually, hooks are placed before and after crucial steps of algorithms, providing subclasses with additional extension points.