Object-oriented design is a very good situation for interviewers to test whether or not the candidates know about coding style well.
You can write codes, and it's really difficult to give awesome code with good coding style.
When get a OOD question.
1 The first thing you should think is to avoid ambiguity.
2 the second thing we should do is to decide the objects in the method.
3 the third thing is that the relation between different objects
4 then the action between objects and improve the coding style
This example also involves the coding pattern, there are so many coding pattern there for use to improve the coding style, I am pretty sure that We need to know about different coding style to improve ourselves.