How to use the elasticsearch2.helpers.bulk function in elasticsearch2

logger.info('Updating page {} / {}'.format(page_end / increment, total_pages))
        else:
            # An extra page is included to cover the edge case where:
            #       max_id == (total_pages * increment) - 1
            # and two additional objects are created during runtime.
            logger.info('Cleaning up...')
        with connection.cursor() as cursor:
            cursor.execute(sql.format(
                index=index,
                page_start=page_start,
                page_end=page_end,
                **kwargs))
            ser_objs = cursor.fetchone()[0]
            if ser_objs:
                total_objs += len(ser_objs)
                helpers.bulk(client(), ser_objs, **es_args)
        page_start = page_end
    return total_objs

"""
    index = index or INDEX
    actions = []
    for node in nodes:
        serialized = serialize(node)
        if serialized:
            actions.append({
                '_op_type': 'update',
                '_index': index,
                '_id': node._id,
                '_type': category or get_doctype_from_node(node),
                'doc': serialized,
                'doc_as_upsert': True,
            })
    if actions:
        return helpers.bulk(client(), actions)

def bulk_update_cgm(cgms, actions=None, op='update', index=None):
    index = index or INDEX
    if not actions and cgms:
        actions = ({
            '_op_type': op,
            '_index': index,
            '_id': cgm._id,
            '_type': 'collectionSubmission',
            'doc': serialize_cgm(cgm),
            'doc_as_upsert': True,
        } for cgm in cgms)

    try:
        helpers.bulk(client(), actions or [], refresh=True, raise_on_error=False)
    except helpers.BulkIndexError as e:
        raise exceptions.BulkUpdateError(e.errors)