from typing import Dict
from typing import Any


def __normalize_properties_to_underscore(data: Dict[str, Any]) -> Dict[str, Any]:
    """Converts microformat2 style property keys from hyphen to underscores."""
    properties = {}
    for key, value in data.get("properties", {}).items():
        properties[key.replace("-", "_")] = value
    return {"type": data["type"], "properties": properties}