<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 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),
        )