def _create_update_statement_for_updating_field_type_metadata(self, update_statement_fields, field_types,
                                                                  field_key):
        """Create update statement for updating field type metadata.

        This method creates an update statement to modify the field type metadata in Vespa.
        It assigns the field type value from field_types to a metadata field in the update statement.

        Args:
            update_statement_fields: Dictionary containing the update statements for fields
            field_types: Dictionary mapping field names to their Marqo field types
            field_key: The field name whose type metadata needs to be updated

        Example:
            If field_key is "title" and field_types["title"] is "string", this will add:
            {"marqo__field_type{title}": {"assign": "string"}} to update_statement_fields
        """
        update_field_type_metadata_key = f'{common.VESPA_DOC_FIELD_TYPES}{{{field_key}}}'
        update_statement_fields[update_field_type_metadata_key] = {"assign": field_types[field_key]}
Create update statement for updating field type metadata.

        This method creates an update statement to modify the field type metadata in Vespa.
        It assigns the field type value from field_types to a metadata field in the update statement.

        Args:
            update_statement_fields: Dictionary containing the update statements for fields
            field_types: Dictionary mapping field names to their Marqo field types
            field_key: The field name whose type metadata needs to be updated

        Example:
            If field_key is "title" and field_types["title"] is "string", this will add:
            {"marqo__field_type{title}": {"assign": "string"}} to update_statement_fields
        
src/marqo/core/semi_structured_vespa_index/semi_structured_vespa_index.py