Tackle Python tasks under time pressure

In a 15-minute coding round, implement a small Python function or class to solve a well-scoped problem within about 5 minutes of coding.

1. State 1–2 clarifying questions you would ask before coding.
2. Enumerate important edge cases and how your solution handles them.
3. Provide clean, readable code and explain your formatting choices.
4. Briefly describe time and space complexity and outline a minimal test plan.