{
    "in_latency_window": [], 
    "operation": "write", 
    "read_preference": {
        "mode": "SecondaryPreferred", 
        "tag_sets": [
            {
                "data_center": "nyc"
            }
        ]
    }, 
    "suitable_servers": [], 
    "topology_description": {
        "servers": [], 
        "type": "Unknown"
    }
}