How to use the scrapelib.cache.CachingSession function in scrapelib

_log.debug('sleeping for %s seconds before retry' % wait)
                if exception_raised:
                    _log.warning('got %s sleeping for %s seconds before retry',
                                 exception_raised, wait)
                else:
                    _log.warning('sleeping for %s seconds before retry', wait)
                time.sleep(wait)

        # out of the loop, either an exception was raised or we had a success
        if exception_raised:
            raise exception_raised
        return resp


# compose sessions, order matters (cache then throttle then retry)
class Scraper(CachingSession, ThrottledSession, RetrySession):
    """
    Scraper is the most important class provided by scrapelib (and generally
    the only one to be instantiated directly).  It provides a large number
    of options allowing for customization.

    Usage is generally just creating an instance with the desired options and
    then using the :meth:`urlopen` & :meth:`urlretrieve` methods of that
    instance.

    :param raise_errors: set to True to raise a :class:`HTTPError`
        on 4xx or 5xx response
    :param requests_per_minute: maximum requests per minute (0 for
        unlimited, defaults to 60)
    :param retry_attempts: number of times to retry if timeout occurs or
        page returns a (non-404) error
    :param retry_wait_seconds: number of seconds to retry after first failure,

resp = super(CachingSession, self).request(method, url, **kwargs)
            resp.fromcache = False
            return resp

        resp = None
        method = method.lower()

        request_key = self.key_for_request(method, url, **kwargs)

        if request_key and not self.cache_write_only:
            resp = self.cache_storage.get(request_key)

        if resp:
            resp.fromcache = True
        else:
            resp = super(CachingSession, self).request(method, url, **kwargs)
            # save to cache if request and response meet criteria
            if request_key and self.should_cache_response(resp):
                self.cache_storage.set(request_key, resp)
            resp.fromcache = False

        return resp