How to use the nbxmpp.modules.dataforms.extend_form function in nbxmpp

def process_result(self, form):
        if self._treeview is not None:
            self._scrolled.remove(self._treeview)
            self._treeview.destroy()
            self._treeview = None
            self._menu = None
            self._label.hide()
            self._scrolled.hide()

        if not form:
            self._label.show()
            return

        form = dataforms.extend_form(node=form)

        fieldtypes = []
        fieldvars = []
        for field in form.reported.iter_fields():
            if field.type_ == 'boolean':
                fieldtypes.append(bool)
            elif field.type_ in ('jid-single', 'text-single'):
                fieldtypes.append(str)
            else:
                log.warning('Not supported field received: %s', field.type_)
                continue
            fieldvars.append(field.var)

        liststore = Gtk.ListStore(*fieldtypes)

        for item in form.iter_records():

def _show_form(self, form):
        if self._dataform_widget is not None:
            self.remove(self._dataform_widget)
            self._dataform_widget.destroy()
        if form is None:
            return
        form = dataforms.extend_form(node=form)
        self._dataform_widget = DataFormWidget(form)
        self._dataform_widget.connect('is-valid', self._on_is_valid)
        self._dataform_widget.validate()
        self._dataform_widget.show_all()
        self.add(self._dataform_widget)

def _build_dataform(self, form, is_form):
        if not is_form:
            return FakeDataFormWidget(form)

        dataform = dataforms.extend_form(node=form)

        form_widget = DataFormWidget(dataform)
        form_widget.connect('is-valid', self._on_is_valid)
        form_widget.validate()
        return form_widget

def _show_form(self, form):
        if self._dataform_widget is not None:
            self.remove(self._dataform_widget)
            self._dataform_widget.destroy()
        if form is None:
            return

        options = {'form-width': 350}

        form = dataforms.extend_form(node=form)
        self._dataform_widget = DataFormWidget(form, options=options)
        self._dataform_widget.connect('is-valid', self._on_is_valid)
        self._dataform_widget.validate()
        self._dataform_widget.show_all()
        self.add(self._dataform_widget)

return

        if configure.getAttr('node') != node:
            self._log.warning('Malformed PubSub configure '
                              'stanza (wrong node): %s', stanza)
            return

        form = configure.getTag('x', namespace=Namespace.DATA)
        if form is None:
            self._log.warning('Malformed PubSub configure '
                              'stanza (no form): %s', stanza)
            return

        app.nec.push_incoming_event(PubSubConfigReceivedEvent(
            None, conn=self._con, node=node,
            form=dataforms.extend_form(node=form)))