anchor.diff:  
   -author("Feng Lee <feng@emqtt.io>").
   
  --include("emqttd_cli.hrl").
  -
  -%% CLI
  --export([cli/1]).
  -
   %% API Function Exports
   -export([start_link/0]).
   
  
positive.code:     {noreply, State}.
  
  terminate(_Reason, _State) ->
      emqttd_ctl:unregister_cmd(trace),
      ok.
  
  code_change(_OldVsn, State, _Extra) ->
  
negative.code:     gen_server:call(?MODULE, all_traces).
  
  init([]) ->
      {ok, #state{level = info, trace_map = #{}}}.
  
  handle_call({start_trace, Who, LogFile}, _From, State = #state{level = Level, trace_map = TraceMap}) ->
  