anchor.diff:      let ctx = g.context in
       let ctx' = Env.rem_proof_ns ctx (path_of_text s) in
       let g' = { g with context = ctx' } in
  -    bind dismiss (fun _ -> add_goals [g']))
  +    bind __dismiss (fun _ -> add_goals [g']))
   
   let addns (s:string) : tac<unit> =
       bind cur_goal (fun g ->
       let ctx = g.context in
       let ctx' = Env.add_proof_ns ctx (path_of_text s) in
       let g' = { g with context = ctx' } in
  -    bind dismiss (fun _ -> add_goals [g']))
  +    bind __dismiss (fun _ -> add_goals [g']))
   
   let rec tac_fold_env (d : direction) (f : env -> term -> tac<term>) (env : env) (t : term) : tac<term> =
       let tn = (SS.compress t).n in
  
positive.code:     bind cur_goal (fun g ->
      bind (new_uvar "dup" g.context g.goal_ty) (fun u ->
      let g' = { g with witness = u } in
      bind dismiss (fun _ ->
      bind (add_irrelevant_goal "dup equation" g.context
                 (U.mk_eq2 (TcTerm.universe_of g.context g.goal_ty) g.goal_ty u g.witness) g.opts) (fun _ ->
      bind (add_goals [g']) (fun _ ->
  
negative.code:         in
          bind (mk_irrelevant_goal "refine_intro refinement" g.context
                      (SS.subst [S.NT (bv, g.witness)] phi) g.opts) (fun g2 ->
          bind __dismiss (fun _ ->
          add_goals [g1;g2])))
  
  let __exact_now set_expected_typ (t:term) : tac<unit> =
  