{"blocks": [{"key": "02863a49", "text": "Question", "type": "header-two", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "f1ef0ada", "text": "Design a scalable notification system that can send messages (email, SMS, push) to millions of users with low latency. Cover requirements gathering, high-level architecture, data model, API design, message prioritization, deduplication, retries, failure handling, scaling strategies, monitoring, and cost considerations.", "type": "unstyled", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}], "entityMap": {}}