anchor.diff:      unascribe = false;
   }
   
  -let rec to_fsteps (s : list<step>) : fsteps =
  +let fstep_add_one s fs =
       let add_opt x = function
           | None -> Some [x]
           | Some xs -> Some (x::xs)
       in
  -    let add_one s fs = match s with
  +    match s with
       | Beta -> { fs with beta = true }
       | Iota -> { fs with iota = true }
       | Zeta -> { fs with zeta = true }
  
positive.code:     weak = false;
      hnf  = false;
      primops = false;
      eager_unfolding = false;
      inlining = false;
      no_delta_steps = false;
      unfold_until = None;
      unfold_only = None;
  
negative.code:     weak : bool;
      hnf  : bool;
      primops : bool;
      no_delta_steps : bool;
      unfold_until : option<S.delta_depth>;
      unfold_only : option<list<I.lid>>;
  