oduleNotFoundError: No module named 'os.environ'

actually I am trying to deploy my app in heroku and I always get this exception in the logs of heroku given that I am using python 3.6.3

2017-10-09T22:14:05.288072+00:00 heroku[web.1]: State changed from crashed 
to starting
2017-10-09T22:14:07.772902+00:00 heroku[web.1]: Starting process with 
command `python BookmarkServer.py`
2017-10-09T22:14:10.065235+00:00 app[web.1]:     import os.environ
2017-10-09T22:14:10.065239+00:00 app[web.1]: ModuleNotFoundError: No module 
named 'os.environ'; 'os' is not a package
2017-10-09T22:14:10.064976+00:00 app[web.1]: Traceback (most recent call 
last):
2017-10-09T22:14:10.064990+00:00 app[web.1]:   File "BookmarkServer.py", 
line 47, in <module>
2017-10-09T22:14:10.158467+00:00 heroku[web.1]: Process exited with status 1
2017-10-09T22:14:10.179803+00:00 heroku[web.1]: State changed from starting 
to crashed