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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_hidden_forum_ids(self, forums, user):
 """ Given a set of forums and a user, returns the list of forums that are not visible by this user. """

        visible_forums = self._get_forums_for_user(
            user, ['can_see_forum', 'can_read_forum', ], use_tree_hierarchy=True,
        )
        return forums.exclude(id__in=[f.id for f in visible_forums])