title: In Google App Engine should I not use instance methods in models?
body: <p>Every time I've seen someone write a model with methods, they use class methods. I assumed this was the way things had to be done, but decided to test my code with instance methods first. I had no problems with using instance methods in my model, but now I'm wondering why everyone always seems to use class methods instead of instance methods. Is there some advantage to using class methods in GAE Models? And will I run into problems down the line if I'm using instance methods?</p>