def add(self, elem, replace=False):
        """Add a requirement.

        :param elem: a string or :class:`Requirement` instance.
        :param replace: if `True`, packages in the set with the same name will
            be removed first.
        """
        if isinstance(elem, text_type):
            elem = Requirement.coerce(elem)
        if replace and elem in self:
            self.remove(elem)
        super(Requirements, self).add(elem)
def delete_forum(forum_id):
    forum = Forum.query.filter_by(id=forum_id).first_or_404()

    involved_users = User.query.filter(Topic.forum_id == forum.id,
                                       Post.user_id == User.id).all()

    forum.delete(involved_users)

    flash(_("Forum deleted."), "success")
    return redirect(url_for("management.forums"))