anchor.diff:          {ok, ?undef | kpro:vsn_ranges()} | {error, any()}.
   get_api_vsns(Pid) ->
     call(Pid, get_api_vsns).
  +
  +-spec get_endpoint(pid()) -> {ok, kpro:endpoint()} | {error, any()}.
  +get_endpoint(Pid) ->
  +  call(Pid, get_endpoint).
   
   %% @hidden
   -spec get_tcp_sock(pid()) -> {ok, port()}.
  
positive.code: %% API
  -export([ all_cfg_keys/0
          , get_api_vsns/1
          , get_tcp_sock/1
          , init/4
          , loop/2
  
negative.code: handle_msg({From, get_api_vsns}, State, Debug) ->
    _ = reply(From, {ok, State#state.api_vsns}),
    ?MODULE:loop(State, Debug);
  handle_msg({From, get_endpoint}, State, Debug) ->
    _ = reply(From, {ok, State#state.remote}),
    ?MODULE:loop(State, Debug);
  handle_msg({From, get_tcp_sock}, State, Debug) ->
    _ = reply(From, {ok, State#state.sock}),
    ?MODULE:loop(State, Debug);
  