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 edit_group(group_id):
    group = Group.query.filter_by(id=group_id).first_or_404()

    form = EditGroupForm(group)

    if form.validate_on_submit():
        form.populate_obj(group)
        group.save()

        if group.guest:
            Guest.invalidate_cache()

        flash(_("Group updated."), "success")
        return redirect(url_for("management.groups", group_id=group.id))

    return render_template("management/group_form.html", form=form,
                           title=_("Edit Group"))