anchor.diff:                    Term.mkApp(t', cvars |> List.map mkFreeV), []
   
                   | None ->
  -                  let tsym = varops.fresh "Tm_arrow" in
  +                  let tsym = varops.mk_unique ("Tm_arrow_" ^ (Util.digest_of_string tkey.hash)) in
                     let cvar_sorts = List.map snd cvars in
                     let caption =
                       if Options.log_queries()
  
positive.code:                      | Some t -> t, []
                       | None ->
                          let cvar_sorts = List.map snd cvars in
                          let fsym = varops.fresh "Exp_abs" in
                          let fdecl = Term.DeclFun(fsym, cvar_sorts, Term_sort, None) in
                          let f = Term.mkApp(fsym, List.map mkFreeV cvars) in
                          let app = mk_Apply f vars in
  
negative.code:               Term.mkApp(t, cvars |> List.map mkFreeV), []
  
              | None ->
                let tsym = varops.mk_unique ("Tm_refine_" ^ (Util.digest_of_string tkey.hash)) in
                let cvar_sorts = List.map snd cvars in
                let tdecl = Term.DeclFun(tsym, cvar_sorts, Term_sort, None) in
                let t = Term.mkApp(tsym, List.map mkFreeV cvars) in
  