anchor.diff:      | CheckNoUvars ->  { fs with check_no_uvars = true }
       | Unmeta ->  { fs with unmeta = true }
       | Unascribe ->  { fs with unascribe = true }
  -    in
  -    List.fold_right add_one s default_steps
  +
  +let rec to_fsteps (s : list<step>) : fsteps =
  +    List.fold_right fstep_add_one s default_steps
   
   type psc = {
       psc_range:FStar.Range.range;
  
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 -> { fs with weak = true }
      | HNF -> { fs with hnf = true }
      | Primops -> { fs with primops = true }
      | Eager_unfolding -> fs // eager_unfolding is not a step
      | Inlining -> fs // not a step
      | NoDeltaSteps ->  { fs with no_delta_steps = true }
      | UnfoldUntil d -> { fs with unfold_until = Some d }
      | UnfoldOnly lids -> { fs with unfold_only = Some lids }
  