Before you proceed to the next chapter, make sure you can answer these questions to your satisfaction:

• How do you organize a Tkinter program in an object-oriented fashion? What are the advantages of using an object-oriented structure as apposed to writing pure procedural code? What are the disadvantages?
• At what stage of programming should you consider drafting a data structure for your GUI program? What are the benefits of having a data structure or model in place?
• What are higher-order functions?
• Why is threading required? What are its advantages and disadvantages?
• What is the difference between a process and a thread?
• What is object persistence? 
• How do you pickle and unpickle objects in Python?
• Besides pickling, what are the other common modes of persisting objects?
• What are ttk widgets? Why are they used?