anchor.diff:  %% @end
   %%--------------------------------------------------------------------
   -spec receive_msg(Msg :: term()) ->
  -    ok | {error, {timeout, UnreceivedMsg :: term()}}.
  +    {ok, ReceivedMsg :: term()} | {error, {timeout, UnreceivedMsg :: term()}}.
   receive_msg(Msg) ->
       receive_msg(Msg, timer:seconds(0)).
   
  
positive.code: %% @equiv receive_any(0)
  %% @end
  %%--------------------------------------------------------------------
  -spec receive_any(Timeout :: timeout()) -> ok | {error, timeout}.
  receive_any(Timeout) ->
      receive
          _ -> ok
      after
          Timeout -> {error, timeout}
      end.
  
negative.code: %% @end
  %%--------------------------------------------------------------------
  -spec receive_msg(Msg :: term(), Timeout :: timeout()) ->
      {ok, ReceivedMsg :: term()} | {error, {timeout, UnreceivedMsg :: term()}}.
  receive_msg(Msg, Timeout) ->
      receive
          Msg -> {ok, Msg}
      after
          Timeout -> {error, {timeout, Msg}}
      end.
  