{"input_data_sample":"2026-03-01T08:15:00Z\n2026-03-01T14:30:00Z\n2026-03-01T08:45:00Z\n2026-03-01T20:00:00Z\n","transformation_instruction":"Parse ISO 8601 timestamps and count occurrences of events per UTC hour, returning a JSON object mapping hour string (e.g. '08', '14') to count.","output_code":"import json\nfrom datetime import datetime\nfrom collections import Counter\n\ndef transform(text):\n    lines = [l for l in text.strip().split('\\n') if l]\n    hours = [datetime.fromisoformat(l.replace('Z', '+00:00')).strftime('%H') for l in lines]\n    return json.dumps(dict(Counter(hours)))\n","output_data_sample":"{\"08\": 2, \"14\": 1, \"20\": 1}"}