anchor.diff:  %% @doc Renders HTML page for response
   -spec render_page(TemplateName :: string(),
                     Req0 :: cowboy_req:req(),
  -                  State :: macaba_web:html_state()) -> handler_return().
  +                  State :: macaba_web:html_state()) ->
  +                     macaba_web:handler_return().
   
   render_page(TemplateName, Req0, State0) ->
     render_page(200, TemplateName, Req0, State0).
  
positive.code: 
  %%%-----------------------------------------------------------------------------
  %% @doc Renders error page with custom message
  -spec render_error(Msg :: iolist()|string()|binary(),
                     Req0 :: cowboy_req:req(),
                     State :: macaba_web:html_state()) -> handler_return().
  
  render_error(Msg, Req0, State0) ->
    State1 = state_set_var(error, Msg, State0),
    {Req1, State2} = render_page(400, "error", Req0, State1),
    {error, {Req1, State2}}.
  
negative.code: -spec redirect_to_thread(BoardId :: binary(),
                           ThreadId :: binary(),
                           Req0 :: cowboy_req:req(),
                           State :: macaba_web:html_state()) ->
                              macaba_web:handler_return().
  
  redirect_to_thread(BoardId, ThreadId, Req, State) ->
     redirect("/board/" ++ macaba:as_string(BoardId) ++ "/thread/"
  