anchor.diff:      initial_labels(Is, [Lbl|Acc]);
   initial_labels([{func_info,_,_,_},{label,Lbl}|_], Acc) ->
       gb_sets:from_list([Lbl|Acc]).
  +
  +drop_upto_label([{label,_}|_]=Is) -> Is;
  +drop_upto_label([_|Is]) -> drop_upto_label(Is);
  +drop_upto_label([]) -> [].
   
   %% ulbl(Instruction, UsedGbSet) -> UsedGbSet'
   %%  Update the gb_set UsedGbSet with any function-local labels
  
positive.code:     case gb_sets:is_member(Lbl, Used) of
  	false ->
  	    Is = case is_unreachable_after(Prev) of
  		     true ->
  			 dropwhile(fun({label,_}) -> false;
  				      (_) -> true
  				   end, Is0);
  		     false -> Is0
  		 end,
  	    rem_unused(Is, Used, Acc);
  
negative.code: %%% on the program state.
  %%% 
  
  -import(lists, [reverse/1,reverse/2,foldl/3]).
  
  module({Mod,Exp,Attr,Fs0,Lc}, _Opt) ->
      Fs = [function(F) || F <- Fs0],
  