def filter_by_widget(self, widget_type):
        """
        Returns a LayoutSlice pointing to fields with widgets of `widget_type`
        """
        self._check_layout_and_form()
        layout_field_names = self.layout.get_field_names()

        # Let's filter all fields with widgets like widget_type
        filtered_fields = []
        for pointer in layout_field_names:
            if isinstance(self.form.fields[pointer[1]].widget, widget_type):
                filtered_fields.append(pointer)

        return LayoutSlice(self.layout, filtered_fields)
Returns a LayoutSlice pointing to fields with widgets of `widget_type`