{"blocks": [{"key": "685b36a7", "text": "Question", "type": "header-two", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "5845dbd4", "text": "Design and implement an object-oriented system for tracking food-delivery driver payments with: 1) add_driver(driver_id, usd_hourly_rate); 2) record_delivery(driver_id, start_time, end_time) using a time format offering ≥1-second precision (deliveries ≤3 h, recorded post-completion); 3) get_total_cost(); then extend with: 4) pay_up_to(pay_time) to mark deliveries paid up to the given Unix epoch time; and 5) get_total_cost_unpaid(). Discuss storage choices, assumptions, OOP practices, and any deviations from production.", "type": "unstyled", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}], "entityMap": {}}