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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 get_for_tag(self, tag):
 """ Returns queryset of Entry instances assigned to specified tag, which can be a PK value, a slug value, or a Tag instance. :param tag: tag PK, slug, or instance. :rtype: django.db.models.query.QuerySet. """

        tag_filter = {'tag': tag}

        if isinstance(tag, six.integer_types):
            tag_filter = {'tag_id': tag}
        elif isinstance(tag, str):
            tag_filter = {'tag__slug': tag}

        return self.filter(id__in=[
            entry_tag.entry_id
            for entry_tag
            in EntryTag.objects.filter(**tag_filter)
        ])