{"ast_node_type":"variable","tokens":[{"end":93,"kind":"keyword","start":0,"text":"let"}]}
        let return_ty_span = main_fn_return_type_span(tcx, main_def_id).unwrap_or(main_span);
        let return_ty = main_fnsig.output();
        let Some(return_ty) = return_ty.no_bound_vars() else {