CODE QUALITY RUBRIC:
- Use only Python standard library
- No input() or interactive I/O; prefer functions with parameters
- Modules: snake_case.py; Classes: CamelCase; functions/vars: snake_case
- Provide module-level docstring and function docstrings (one-liners ok)
- Keep lines <= 100 chars where practical
- Include README.md with usage instructions
- Include at least one simple test (unittest) if any logic exists

