{"ast_node_type":"other","tokens":[{"end":97,"kind":"keyword","start":0,"text":"(0..NUM_PREINTERNED_TY_VARS).map(|n|"}]}
            (0..NUM_PREINTERNED_TY_VARS).map(|n| mk(Infer(ty::TyVar(TyVid::from(n))))).collect();
        let ty_vars =
        let fresh_tys: Vec<_> =