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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def published(self, for_user=None):
 """ Return only published entries for the current site. """

        if appsettings.FLUENT_BLOGS_FILTER_SITE_ID:
            qs = self.parent_site(settings.SITE_ID)
        else:
            qs = self

        if for_user is not None and for_user.is_staff:
            return qs

        return qs \
            .filter(status=self.model.PUBLISHED) \
            .filter(
                Q(publication_date__isnull=True) |
                Q(publication_date__lte=now())
            ).filter(
                Q(publication_end_date__isnull=True) |
                Q(publication_end_date__gte=now())
            )