anchor.diff:  %%%----------------------------------------------------------------------
   
   new_variable() ->
  -    [{used, Used}] = ets:lookup(?NT_USED, used),
  +    Used = get(?NT_USED),
       Fresh = erl_syntax_lib:new_variable_name(Used),
  -    ets:insert(?NT_USED, {used, sets:add_element(Fresh, Used)}),
  +    put(?NT_USED, sets:add_element(Fresh, Used)),
       erl_syntax:variable(Fresh).
   
   new_underscore_variable() ->
  -    [{used, Used}] = ets:lookup(?NT_USED, used),
  +    Used = get(?NT_USED),
       new_underscore_variable(Used).
   
   new_underscore_variable(Used) ->
  
positive.code:     {'ok', [mfb()]} | 'error'.
  
  instrument_and_compile(Files, Includes, Defines) ->
      instrument_and_compile_aux(Files, Includes, Defines, []).
  
  instrument_and_compile_aux([], _Includes, _Defines, Acc) ->
      {ok, lists:reverse(Acc)};
  instrument_and_compile_aux([File|Rest], Includes, Defines, Acc) ->
      case instrument_and_compile_one(File, Includes, Defines) of
          error -> error;
          Result -> instrument_and_compile_aux(Rest,Includes,Defines,[Result|Acc])
      end.
  
  %% Instrument and compile a single file.
  
negative.code:     lists:foreach(Fun, ModsToPurge).
  
  %% @spec instrument_and_compile(Files::[file:filename()],
  %%                              Includes::[file:name()],
  %%                              Defines::macros())
  %%          -> {'ok', [mfb()]} | 'error'
  %% @doc: Instrument and compile a list of files.
  %%
  %% Each file is first validated (i.e. checked whether it will compile
  