How to use the pybatfish.question.bfq.differentialReachability function in pybatfish

console.setLevel(logging.ERROR)
        logging.getLogger('').addHandler(console)

    load_questions()
    bf_init_snapshot(args.candidate, name='candidate')
    bf_init_snapshot(args.failure, name='failure')

    bf_set_snapshot('candidate')
    csFailed = test_config_sanity(False)
    cpFailed = test_controlplane(False)
    dpFailed = test_dataplane(False, fromNode='leaf-3')

    logging.info("\nProgress: analysing failure conditions")
    bf_set_snapshot('failure')
    dpFailedoutage = test_dataplane(False, fromNode='leaf-3')
    rr = bfq.differentialReachability().answer(snapshot='candidate', reference_snapshot='failure')
    print_reduced_rechability(rr.get('answerElements')[0])

    

    

    return 0 if not any([cpFailed, dpFailed, csFailed, dpFailedoutage]) else 1

for i in range(MAX_CHAOS):
    failed_link1_index = random.randint(0, len(links) - 1)
    failed_link2_index = random.randint(0, len(links) - 1)
    print(" - Deactivating Links:{} + {}".format(links.loc[failed_link1_index].Interface,
                                                  links.loc[failed_link2_index].Interface))

    FAIL_SNAPSHOT_NAME = "fail_snapshot"
    bf_fork_snapshot(
        BASE_SNAPSHOT_NAME,
        FAIL_SNAPSHOT_NAME,
        deactivate_interfaces=[links.loc[failed_link1_index].Interface,
                               links.loc[failed_link2_index].Interface],
        overwrite=True
    )

    answer = bfq.differentialReachability(
        headers=HeaderConstraints(dstIps='server2')
    ).answer(
        snapshot=FAIL_SNAPSHOT_NAME,
        reference_snapshot=BASE_SNAPSHOT_NAME
    ).frame()

    if len(answer) > 0:
        print("[FAIL] No reachability discovered for the following flow(s)...")
        print_diff_reachability(answer)
        sys.exit(1)

print("[SUCCESS] No reachability issues found after {} rounds of chaos!".format(MAX_CHAOS))