def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
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"))