"Defining OO as based on the use of class hierarchies and virtual functions is also practical in that it provides some guidance as to where OO is likely to be successful."

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If you want to be successful, you have to jump, there's no way around it. When you jump, I can assure you that your parachute will not open right away. But if you do not jump, your parachute will never open. If you're safe, you'll never soar!

— Steve Harvey