Python: Mutation and Copying Question When does mutation and copying need a refactor? (Click to reveal answer) Answer When the rule is no longer easy to explain, test, or change without surprising nearby code. Refactoring is justified by reduced risk and better clarity, not by aesthetic preference alone. Additional NotesWhen does mutation and copying need a refactor? Track: Python Topic: Code Safety Focus: Mutation and Copying Topics: Code Safety Mutation and Copying Python