anchor.diff:                   C when C == squery; C == equery ->
                        State;
                    _ ->
  -                     State#state{queue = queue:drop(Q)}
  +                     sync_required(State#state{queue = queue:drop(Q)})
                end,
       {noreply, State2};
   
  
positive.code:     notify_async(State, {notification, Channel, Pid, Payload}),
      {noreply, State}.
  
  to_binary(B) when is_binary(B) -> B;
  to_binary(L) when is_list(L)   -> list_to_binary(L).
  
  
negative.code:                 async,
                  parameters = [],
                  columns,
                  sync_required,
                  txstatus}).
  
  %% -- client interface --
  