Trying to delete a poll or even opening vote from django admin raises an error.

[ArijitWeird]

I am using django 1.10.8 and django-simple-poll v0.2.1. Here is the error that i am getting:

Exception Type: | TypeError

isinstance() arg 2 must be a class, type, or tuple of classes and types ****/python2.7/site-packages/poll/models.py in str, line 89