Prerequisites
Python 3.10+ and the standard library. These supplemental case references require no pip packages.
Steps and expected result
Run from the extracted pack directory. Expected JSON contains retail sales_cents 70000. On Windows the launcher may be py -3. A missing file error means the three CSV files are not beside the script; do not fix it by deleting validation.
python3 --version
python3 case-reference.pyVerification
Check the input row count and case control totals before attempting a larger exercise. Record your operating system/tool version when asking for support. Never include passwords or private source records.
Independent check
Explain which output proves the setup works and which capabilities remain untested. Do not disable security settings to make an exercise run.
Try the activity before reading its reference. Keep your sources, commands and assumptions with your work. Companion activities are unsaved self-practice and do not award a certificate or change lesson progress.