anchor.diff:  %%% API
   %%%===================================================================
   
  -%% debug & test
   start() ->
  -    start([]).
  -start(Opts) ->
  -    gen_server:start({local, ?SERVER}, ?MODULE, [Opts], []).
  +    application:start(netlink).
   
   i() ->
       gen_server:call(?SERVER, {list,[]}).
  
positive.code: 
  unsubscribe(Ref) ->
      gen_server:call(?SERVER, {unsubscribe,Ref}).
  
  get_root(What,Fam) ->
      get(What,Fam,[root,match,request],[]).
  
negative.code: -export([i/0, list/1]).
  -export([subscribe/1, subscribe/2, subscribe/3]).
  -export([unsubscribe/1]).
  -export([invalidate/2]).
  -export([get_root/2, get_match/3, get/4]).
  
  -include_lib("lager/include/log.hrl").
  