anchor.diff:  request_event( Pid, Event ) ->
       { From, To } = from_to( self(), Pid ),
       Pid ! { { get_event,  Event }, From },
  -    wait_event( To ).
  +    wait( To ).
   
   -spec request_event_async( pid(), string() ) -> { ok, { pid(), reference() } }.
   request_event_async( Pid, Event ) ->
  
positive.code: stop( Pid ) ->
      { From, To } = from_to( self(), Pid ),
      Pid ! { stop, From },
      wait_stop( To ).
  
  -spec stop_async( pid() ) -> { ok, { pid(), reference() } } | { error, timeout }.
  stop_async( Pid ) ->
  
negative.code: 
      { ok, From2 } = request_event_async( Pid, "SomeEvent" ),
      ResEvent = receive
          { Res2, From2 } -> Res2
      after
          ?DRIVER_TIMEOUT -> timeout
      end,
  
      { ok, From3 } = stop_async( Pid ),
      ResStop = receive
          { Res3, From3 } -> Res3
      after
          ?DRIVER_TIMEOUT -> timeout
      end,
  