How to use the cachier.base_core._BaseCore.__init__ function in cachier

def __init__(self, mongetter, stale_after, next_time):
        if 'pymongo' not in sys.modules:
            warnings.warn((
                "Cachier warning: pymongo was not found. "
                "MongoDB cores will not function."))
        _BaseCore.__init__(self, stale_after, next_time)
        self.mongetter = mongetter
        self.mongo_collection = self.mongetter()
        index_inf = self.mongo_collection.index_information()
        if _MongoCore._INDEX_NAME not in index_inf:
            func1key1 = IndexModel(
                keys=[('func', ASCENDING), ('key', ASCENDING)],
                name=_MongoCore._INDEX_NAME)
            self.mongo_collection.create_indexes([func1key1])

def __init__(self, stale_after, next_time, reload, cache_dir):
        _BaseCore.__init__(self, stale_after, next_time)
        self.cache = None
        self.reload = reload
        self.cache_dir = DEF_CACHIER_DIR
        if cache_dir is not None:
            self.cache_dir = cache_dir
        self.expended_cache_dir = os.path.expanduser(self.cache_dir)
        self.lock = threading.RLock()
        self.cache_fname = None
        self.cache_fpath = None