ImportError: No module named utils on websocket_messaging

[Luis Sucuc]

I am trying to use sockets as follows

python gluon/contrib/websocket_messaging.py -k 123 -p 8888

but I receive the following error

Traceback (most recent call last):
  File "gluon/contrib/websocket_messaging.py", line 96, in <module>
    import gluon.utils
ImportError: No module named utils

SO: Ubuntu 18.04.3 LTS

Version

2.18.5-stable+timestamp.2019.04.08.04.22.03
(Running on Rocket 1.2.6, Python 2.7.15+)