Using gunicorn to run app error

I have gunicorn successfully installed

Every time I run this command:

$ gunicorn hello.wsgi:application --bind example.com:8001

I get this error:

[INFO] Starting gunicorn 18.0
[ERROR] Invalid address: ('example.com', 8001)

I am following this tutorial:

http://michal.karzynski.pl/blog/2013/06/09/django-nginx-gunicorn-virtualenv-supervisor/