def __init__(self, cache_file, cache, update_interval):
self.cache_file = cache_file<EOL>self.cache = cache<EOL>self.update_interval = update_interval<EOL>
Initializes new :class:`Cache` object.

        :param str cache_file: full path to the loaded cache file.
        :param ~shelve.Shelve cache: a Shelve object, with cache loaded.
        :param int update_interval: number of seconds the cache is considered to be
                                    up-to-date without calling any external resources.