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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 entries_published(queryset):
 """ Return only the entries published. """

    now = timezone.now()
    return queryset.filter(
        models.Q(start_publication__lte=now) |
        models.Q(start_publication=None),
        models.Q(end_publication__gt=now) |
        models.Q(end_publication=None),
        status=PUBLISHED, sites=Site.objects.get_current())