anchor.diff:  
   debug(Format, Args, Level) ->
     FullFormat = lists:concat(["debug level ", Level, ": ", Format]),
  -  gen_server:cast(erruby_debug_pid, #{level => Level, format => FullFormat, args => Args}).
  +  gen_server:call(erruby_debug_pid, #{level => Level, format => FullFormat, args => Args}).
   
   debug_1(Format, Args) ->
     debug(Format, Args, 1).
  
positive.code:   io:format("Got unkwon info:~n~p~n", [Info]),
    {ok, State}.
  
  
  handle_call(_Req, _From, State) ->
    io:format("handle unknow call ~p ~p ~p ~n",[_Req, _From, State]),
  
negative.code: handle_cast(#{new_level := NewLevel}, State) ->
    {noreply, State#{ debug_level => NewLevel } };
  
  handle_cast(_Req, State) ->
    io:format("handle unknown cast ~p ~p ~n",[_Req, State]),
    NewState = State,
  