def cache_path(self):
        """
        make a directory to store all caches
        :return: cache path
        """
        cache_path = os.path.join(self.root_path, 'cache')
        if not os.path.exists(cache_path):
            os.mkdir(cache_path)
        return cache_path

        make a directory to store all caches
        :return: cache path
        
lib/dataset/imdb.py