anchor.diff:        true
       | _ ->
         false
  -
  -// TODO: GM: kinda flaky and ill named
  -let is_fstar_tactics_embed t =
  -    match (U.un_uinst t).n with
  -    | Tm_fvar fv -> S.fv_eq_lid fv SC.fstar_refl_embed_lid
  -    | _ -> false
   
   let rec norm : cfg -> env -> stack -> term -> term =
       fun cfg env stack t ->
  
positive.code: 
  type stack = list<stack_elt>
  
  
  
  let mk t r = mk t None r
  let set_memo r t =
  
negative.code:             | Tm_type u ->
                mk (Tm_type (norm_universe cfg env u)) t.pos
  
              | Tm_uinst(t', us) -> (* head symbol must be an fvar *)
                if is_fstar_tactics_embed t'
                then t
                else mk_Tm_uinst t' (List.map (norm_universe cfg env) us)
  
              | Tm_bvar x ->
                begin match lookup_bvar env x with
  