{"ast_node_type":"variable","tokens":[{"end":62,"kind":"keyword","start":0,"text":"let"}]}
        let coroutine_kind_ty = args.as_coroutine().kind_ty();
    ) -> Result<&'tcx CoroutineLayout<'tcx>, &'tcx LayoutError<'tcx>> {
        let mir = self.optimized_mir(def_id);