{"ast_node_type":"variable","tokens":[{"end":59,"kind":"keyword","start":0,"text":"let"}]}
            let gpl_owner = ast_mut_from_text::<N>(before);
        fn check_create_gpl<N: GenericParamsOwnerEdit + fmt::Display>(before: &str, after: &str) {
            gpl_owner.get_or_create_generic_param_list();