Infinite generator pattern

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Accepted Answer

A generator with while True never raises StopIteration on its own - it is infinite. It only produces values when asked. The list comprehension calls next(gen) exactly 3 times, getting 5, 6, 7, then stops. The generator is paused but not destroyed - the next call would yield 8. This pattern is used in ID generators, sequence producers, and anywhere you want an on-demand stream with no predefined end.