Error while running : int_ref_topology.py

[zenhox]

Traceback (most recent call last): File "./int_ref_topology.py", line 17, in from int_cfg import * File "/home/hox/workspace/p4factory/mininet/int_cfg.py", line 20, in from mininet.util import ( quietRun, fixLimits, numCores, ensureRoot, ImportError: cannot import name waitListening

I spare no effort to install this demo. How can I solve this issue.