anchor.diff:  
   let log_primops cfg f =
       if cfg.debug.primop then f () else ()
  +
  +let log_unfolding cfg f =
  +    if cfg.debug.unfolding then f () else ()
   
   let is_empty = function
       | [] -> true
  
positive.code:         Some (cfg, List.tl stack)
  
      | _ ->
          failwith <| BU.format1 "Unexpected unfolding result, (%s, %s, %s)" (string_of_res res)
  
  let rec norm : cfg -> env -> stack -> term -> term =
      fun cfg env stack t ->
  
negative.code:     {tcenv=e;
       debug = { gen = Env.debug e (Options.Other "Norm")
               ; primop = Env.debug e (Options.Other "Primops")
               ; unfolding = Env.debug e (Options.Other "Unfolding")
               ; b380 = Env.debug e (Options.Other "380")
               ; wpe  = Env.debug e (Options.Other "WPE")
               ; norm_delayed = Env.debug e (Options.Other "NormDelayed")
  