How to use the pyral.cargotruck.CargoTruck function in pyral

def test_cargo_truck_init():
    cgo = CargoTruck(['a', 'b'], 2)
    assert len(cgo.orders) == 2
    assert cgo.orders[0] == 'a'
    assert cgo.num_loaders == 2
    print("at the end of the rope")

items_remaining = self._servable - self._served
        num_threads = self.max_threads
        max_chunksize = self.pageSize * num_threads
        if items_remaining - max_chunksize < 0:
            full, leftovers = divmod(items_remaining, self.pageSize)
            num_threads = full + (1 if leftovers else 0)
        stixes = [i+1 for i in range(num_threads)] 
        page_urls = [re.sub('&start=\d+', '&start=%s' % (self.startIndex + (i * self.pageSize)), self.resource)
                        for i in stixes]

        success = False
        exc     = None
        delays = [0, 2, 5]
        for delay in delays:
            time.sleep(delay)
            cgt = CargoTruck(page_urls, num_threads)
            try:
                cgt.load(self.session, 'get', 15)
                payload = cgt.dump()
                success = True
                break
            except:
                exc_name, exc_desc = sys.exc_info()[:2]
                anomaly = "RallyResponse.next.__retrieveNextPage.__retrievePages caught exception " +\
                          "in threaded request/response activity: %s, %s" % (exc_name, exc_desc)
                pg1, pg2 = (self.startIndex + self.pageSize), (self.startIndex + (self.pageSize*num_threads))
                notice = "Retrying the page_urls for the page group startIndexes: %d -> %d" % (pg1, pg2)
                print(notice)

        if not success:
            raise RallyResponseError("Unable to retrieve %d chunks of data" % num_threads)