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The Open-Closed Principle (OCP) states that software entities (classes, modules, functions, etc.) should be open for ____ but closed for ____. This means that once a software entity is implemented and tested, it should not be ____ to add new functionality. Instead, new functionality should be added by extending or ____ the existing entity.

The OCP promotes extensibility and avoids the need to modify ____ code, reducing the risk of introducing bugs. It encourages the use of abstraction and ____ to allow for easy addition of new features.