def index(self, record):
        """Index a record.

        The caller is responsible for ensuring that the record has already been
        committed to the database. If a newer version of a record has already
        been indexed then the provided record will not be indexed. This
        behavior can be controlled by providing a different ``version_type``
        when initializing ``RecordIndexer``.

        :param record: Record instance.
        """
        index, doc_type = self.record_to_index(record)

        return self.client.index(
            id=str(record.id),
            version=record.revision_id,
            version_type=self._version_type,
            index=index,
            doc_type=doc_type,
            body=self._prepare_record(record, index, doc_type),
        )