':param namespace: redis namespace (default: ``\'requests-cache\'``)
:param connection: (optional) ``redis.StrictRedis``'

def __init__(self, namespace='requests-cache', **options):

    super(RedisCache, self).__init__()
    self.responses = RedisDict(namespace, 'responses', options.get('connection'))
    self.keys_map = RedisDict(namespace, 'urls', self.responses.connection)
