anchor.diff:          ?PRINT("failed to cluster with ~p~n", [Node])
   	end.
   
  -add_user(Username, Password) ->
  +add_user([Username, Password]) ->
   	?PRINT("~p", [emqtt_auth:add(list_to_binary(Username), list_to_binary(Password))]).
   
  -delete_user(Username) ->
  +delete_user([Username]) ->
   	?PRINT("~p", [emqtt_auth:delete(list_to_binary(Username))]).
  
positive.code: 
  -include("emqtt.hrl").
  
  -compile(export_all).
  	
  status() ->
      {InternalStatus, _ProvidedStatus} = init:get_status(),
      ?PRINT("Node ~p is ~p~n", [node(), InternalStatus]),
      case lists:keysearch(emqtt, 1, application:which_applications()) of
  
negative.code: 		?PRINT_MSG("emqtt is running~n")
      end.
  
  cluster_info([]) ->
      Nodes = [node()|nodes()],
      ?PRINT("cluster nodes: ~p~n", [Nodes]).
  
  cluster([Node]) ->
  	case net_adm:ping(list_to_atom(Node)) of
  	pong ->
  		?PRINT("cluster with ~p successfully.~n", [Node]);
  