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← CoursesSenior Deep-DivesModule 11 · Decorator patterns at scaleWrite: unique_by() — order-preserving deduplication with a key functionwrite161 / 161
+175 XP
Task
Implement `unique_by(seq, key=None)`. The test runs 4 cases: int dedupe (no key), string dedupe by length, dict dedupe by id field, and empty input.
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