anchor.diff:  
   %% @private
   make_put_fun() ->
  -    Exp = case is_21() of
  +    Exp = case is_21_2() of
           true ->
               "
                   do_config_put(Key, Value) ->
  
positive.code:     forms_expression(Exp).
  
  
  %% @private
  is_21() ->
      erlang:system_info(otp_release) >= "21".
  
  
  %% @private
  
negative.code: 
  %% @private
  make_get_fun() ->
      Exp = case is_21_2() of
          true ->
              "
                  do_config_get(Key) ->
  