@property
    def author(self):
        """
        Easy way to get a combination of authors without having to worry which
        fields are set (author/one-off author)
        """
        import warnings
        warnings.warn('Story.author property is being deprecated, use '
                      '`Story.author_display` instead', DeprecationWarning)

        AuthorModel = models.get_model(*settings.AUTHOR_MODEL.split("."))
        link = '<a href="%s">%s %s</a>'
        if AuthorModel.__module__ == 'django.contrib.auth.models':
            authors = [link % (
                i.get_profile().get_absolute_url(),
                i.first_name,
                i.last_name) for i in self.authors.all()]
        else:
            authors = [link % (i.get_absolute_url(), i.first_name, i.last_name)
                       for i in self.authors.all()]
        if self.non_staff_author:
            authors.append(self.non_staff_author)
        if len(authors) > 1:
            author_string = (", ".join(authors[:-1]), authors[-1]) % "%s and %s"
        elif len(authors) == 1:
            author_string = authors[0]
        else:
            author_string = ''
        return mark_safe(author_string)
dataset/ETHPy150Open callowayproject/django-stories/stories/models.py/Story.author/swapped operands of `%`