def load(self, requirements_file=None):
        """Load or reload requirements from a requirements.txt file.

        :param requirements_file: if not given, the filename used from
            initialization will be read again.
        """
        if requirements_file is None:
            requirements_file = self.filename
            if requirements_file is None:
                raise ValueError("no filename provided")
        elif isinstance(requirements_file, text_type):
            requirements_file = Path(requirements_file)
        self.clear()
        with requirements_file.open() as f:
            self.loads(f.read())

        if isinstance(requirements_file, (text_type, Path)):
            self.filename = requirements_file
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"))