anchor.diff:                                      | Some attrs -> BU.for_some (attr_eq attr) attrs
                                       | None -> true
                                       end)
  -                  else should_delta
                   end
               in
   
  
positive.code:             //log cfg (fun () -> BU.print "Tm_fvar case 0\n" []) ;
              rebuild cfg env stack t
  
            // we don't unfold dm4f actions unless reifying
            | Tm_fvar fv when Env.is_action cfg.tcenv (S.lid_of_fv fv) ->
              let b = should_reify cfg stack in
              log cfg (fun () -> BU.print2 ">>> For DM4F action %s, should_reify = %s\n"
                                       (Print.term_to_string t)
                                       (string_of_bool b));
              if b
              then do_unfold_fv cfg env (List.tl stack) t fv
              else rebuild cfg env stack t
  
            | Tm_app(hd, args)
              when U.is_fstar_tactics_embed hd
                || (U.is_fstar_tactics_quote hd && cfg.steps.no_delta_steps)
  
negative.code:                  let stack = us::stack in
                   norm cfg env stack t'
  
            // we don't unfold dm4f actions unless reifying
            | Tm_fvar fv when Env.is_action cfg.tcenv (S.lid_of_fv fv) ->
              let b = should_reify cfg stack in
              log cfg (fun () -> BU.print2 ">>> For DM4F action %s, should_reify = %s\n"
                                       (Print.term_to_string t)
                                       (string_of_bool b));
              if b
              then do_unfold_fv cfg env (List.tl stack) t fv
              else rebuild cfg env stack t
  
            | Tm_fvar f ->
              let should_delta =
                  cfg.delta_level |> BU.for_some (function
  