anchor.diff:  rename_var(Old, _) -> Old.
   
   rename_phi_vars([{Var,L}|As], Preds, Ren) ->
  -    case gb_sets:is_member(L, Preds) of
  +    case cerl_sets:is_element(L, Preds) of
           true ->
               [{rename_var(Var, Ren),L}|rename_phi_vars(As, Preds, Ren)];
           false ->
  
positive.code:     {Blocks,Acc}.
  
  linearize_1([L|Ls], Blocks, Seen0, Acc0) ->
      case gb_sets:is_member(L, Seen0) of
          true ->
              linearize_1(Ls, Blocks, Seen0, Acc0);
          false ->
              Seen1 = gb_sets:insert(L, Seen0),
              Block = maps:get(L, Blocks),
              Successors = successors(Block),
              {Acc,Seen} = linearize_1(Successors, Blocks, Seen1, Acc0),
  
negative.code:       Labels :: [label()].
  
  rpo(From, Blocks) ->
      Seen = cerl_sets:new(),
      {Ls,_} = rpo_1(From, Blocks, Seen, []),
      Ls.
  
  