def __init__(self, mongo_client, index, collection):
        """
        :param mongo_client: MongoClient instance
        :type mongo_client: MongoClient
        :param index: database index
        :type index: str
        :param collection: index collection
        :type collection: str
        """
        self._mongo_client = mongo_client
        self._index = index
        self._collection = collection
def __init__ ( self , mongo_client , index , collection ) : self . _mongo_client = mongo_client self . _index = index self . _collection = collection
:param mongo_client: MongoClient instance
        :type mongo_client: MongoClient
        :param index: database index
        :type index: str
        :param collection: index collection
        :type collection: str