Work out a music teacher's term fees with credits for lessons the teacher missed and a sibling discount

# Work out a music teacher's spring term fees Inputs: `pupils.csv` (each pupil: family, lesson minutes, lessons the teacher missed, lessons the pupil missed) and `rates.json` (the price of one lesson of each length and the number of lessons in the term). Every amount is in pounds. Fee rules: - Term fee = lessons in the term x the lesson price for the pupil's lesson length, minus a full-price credit for each lesson the teacher missed; lessons the pupil missed are not credited. - In a family with more than one pupil, every pupil except the one with the highest term fee gets 10% off their term fee (rounded to the cent half-up); a pupil with no brother or sister in pupils.csv gets no discount. - Due = term fee - sibling discount. Write `out/fees.json`: `{"term_fee": {"<pupil>": <term fee after credits>, ...}, "sibling_discount": {...}, "due": {...}, "family_total": {"<family>": <sum of due>, ...}}` with every pupil and family in `pupils.csv`. ## How this run works - Work on your own: nobody will answer questions in this task, and writing to `ask/` counts against the run. - Write only under `out/`. Create `out/` if it is missing. Inputs are synthetic; don't fetch anything from the network. - Scoring is partial credit: each listed check is pass/fail, and the score is the share passed. Numbers are compared to within 0.005 unless the task says otherwise.