anchor.diff:  
   
   test_poll_device_event( Pid ) ->
  -    Token = make_ref(),
  +    Tag = make_ref(),
       meck:expect( lurch_dev, request_event_async,
  -                 fun( _, _ ) -> Token end ),
  +                 fun( _, _ ) -> { ok, Tag } end ),
       DeviceId = make_ref(),
       Event = myevent,
       Device = #device{ id = DeviceId, events = [ Event ] },
  
positive.code:     { noreply, S2 } = handle_cast( { poll_device_event, invalid, Event }, S0 ),
      { noreply, S3 } = handle_cast( { poll_device_event, DeviceId, invalid }, S0 ),
  
      [ { "valid device and event", ?_assertEqual( [ Token ], S1#state.polls ) }
      , { "invalid device", ?_assertEqual( S0, S2 ) }
      , { "invalid event", ?_assertEqual( S0, S3 ) }
      ].
  
negative.code: handle_cast( { poll_device_event, DeviceId, Event }, State ) ->
      case maybe_get_device_pid( DeviceId, Event, State#state.devices ) of
          { ok, Pid } ->
              { ok, Tag } = lurch_dev:request_event_async( Pid, Event ),
              NewState = State#state{ polls = [ Tag | State#state.polls ] },
              { noreply, NewState };
          _ ->
              % FIXME - log?
  