def _extract_map_name_from_field(self, field_name: str) -> str:
        """Extract the map name from a flattened field name.
        For fields like "map_name.key_name", this method extracts the map name portion.
        
        Args:
            field_name: The flattened field name (e.g., "map1.key1")
        Returns:
            The map name portion of the field (e.g., "map1")
        """
        if "." in field_name:
            return field_name.split(".", 1)[0]
        return field_name
Extract the map name from a flattened field name.
        For fields like "map_name.key_name", this method extracts the map name portion.
        
        Args:
            field_name: The flattened field name (e.g., "map1.key1")
        Returns:
            The map name portion of the field (e.g., "map1")
        
src/marqo/core/semi_structured_vespa_index/semi_structured_vespa_index.py