def index(obj, index=INDEX_NAME, doc_type=DOC_TYPE):
    """
    Index the given document.

    https://elasticsearch-py.readthedocs.io/en/master/api.html#elasticsearch.Elasticsearch.index
    https://www.elastic.co/guide/en/elasticsearch/reference/current/docs-index_.html
    """
    doc = to_dict(obj)

    if doc is None:
        return

    id = doc.pop('id')

    return es_conn.index(index, doc_type, doc, id=id)