Keep reusable code clean and production-ready: reusable/algorithmic functions should be side-effect free (no `print()`), and all executable/demo/driver code must be under an `if __name__ == "__main__":` guard. Also keep imports at the top and sorted/PEP8-compliant. Example (move prints + examples): ```python def quick_select(items: list[int], index: int) -> int: # reusable logic: no printing, no prompting ... def _demo() -> None: prices = [7, 1, 5, 3, 6, 4] print("Example:", quick_select(prices, 3)) if __name__ == "__main__": _demo() ``` Checklist: - No `print()`/debug logging in core algorithm/library functions (return values instead). - Put example usage, manual tests, and script entry points behind `if __name__ == "__main__":`. - Put all imports at the top of the file; sort/group them per lint rules. - Ensure type hints and function signatures are consistent and non-redundant (don’t omit required annotations for public functions).