anchor.diff:                                          (Print.term_to_string t)
                                           (BU.string_of_int (List.length env))
                                           (stack_to_string (fst <| firstn 4 stack)));
  +        log_cfg cfg (fun () -> BU.print1 ">>> cfg = %s\n" (cfg_to_string cfg));
           match t.n with
             | Tm_unknown
             | Tm_constant _
  
positive.code:     in_full_norm_request: bool;
      weakly_reduce_scrutinee:bool;
  }
  
  let default_steps : fsteps = {
      beta = true;
  
negative.code: type debug_switches = {
      gen              : bool;
      top              : bool;
      cfg              : bool;
      primop           : bool;
      unfolding        : bool;
      b380             : bool;
  