Fill used labels into filename

def get_filename_filled_with_checked_labels(self, labels=None):
        """ Fill used labels into filename """
        if labels is None:
            labels = self.slab_wg.action_check_slab_ui()
        string_labels = imma.get_nlabels(slab=self.slab_wg.slab, labels=labels, return_mode="str")
        filename = self.vtk_file.format(
            "-".join(string_labels))
        return filename