anchor.diff:  
   start_link(Opts) ->
     gen_server:start_link(?MODULE, Opts, []).
  +stop(Pid) ->
  +  gen_server:cast(Pid, stop).
   
   ping(Pid) ->
     gen_server:call(Pid, ping).
  
positive.code: handle_info(_Info, State) ->
    {noreply, State}.
  
  terminate(_Reason, _State) ->
    ok.
  
  code_change(_OldVsn, State, _Extra) ->
  
negative.code: order_cancel(Pid, Order) ->
    PayloadRec = #seto_order_cancel{order=Order},
    gen_server:call(Pid, {order_cancel, PayloadRec}).
  
  subscribe(Pid, Group) ->
    PayloadRec = #seto_market_subscription{group=Group},
    gen_server:call(Pid, {market_subscription, PayloadRec}).
  
  unsubscribe(Pid, Group) ->
    PayloadRec = #seto_market_unsubscription{group=Group},
    gen_server:call(Pid, {market_unsubscription, PayloadRec}).
  
  %% ------------------------------------------------------------------
  %% gen_server Function Definitions
  