[1.6.x] Fixed #20858 -- Removed erroneous import in tutorial 2.

You can improve that by giving that method (in :file:`polls/models.py`) a few

attributes, as follows::

    import datetime

    from django.utils import timezone

    from django.db import models

    from polls.models import Poll

    class Poll(models.Model):

        # ...

        def was_published_recently(self):