anchor.diff:         //NS: 01/24 ... looks redundant
           bind (add_implicits implicits.implicits) (fun _ ->
           // We solve with (), we don't care about the witness if applying a lemma
  -        bind (solve goal U.exp_unit) (fun _ ->
  +        bind (solve' goal U.exp_unit) (fun _ ->
           let is_free_uvar uv t =
               let free_uvars = List.map (fun x -> x.ctx_uvar_head) (BU.set_elements (SF.uvars t)) in
               List.existsML (fun u -> UF.equiv u uv) free_uvars
  
positive.code:     Err.log_issue (goal_type g).pos
          (Errors.Warning_TacAdmit, BU.format1 "Tactics admitted goal <%s>\n\n"
                      (goal_to_string g));
      solve g U.exp_unit)
  
  let fresh () : tac<Z.t> =
      bind get (fun ps ->
  
negative.code: let trivial () : tac<unit> =
      bind (cur_goal ()) (fun goal ->
      if istrivial (goal_env goal) (goal_type goal)
      then solve' goal U.exp_unit
      else fail1 "Not a trivial goal: %s" (tts (goal_env goal) (goal_type goal))
      )
  
  