{"ast_node_type":"variable","tokens":[{"end":63,"kind":"keyword","start":0,"text":"let"}]}
        let input_output = rust_ir::CoroutineInputOutputDatum {
        let len = subst.len(Interner);
            resume_type: TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, len - 3))