anchor.diff:      stop(rotate_right),
       firmata:stop().
   
  +emergency_stop(Device) ->
  +    setup(Device),
  +    stop(forward),
  +    firmata:stop().
  +
   % Private API
   
   setup(Device) ->
  
positive.code: -define(SLEEP, 10).
  -define(STOP_SLEEP, 30).
  -define(TEST_SLEEP, 3000).
  -define(FWD_SPEED, 255).
  -define(BWD_SPEED, 200).
  -define(ROTATE_SPEED, 200).
  
negative.code:     Distance = firmata:digital_read(?PING),
      case Distance of
          Value when Value > ?THRESHOLD andalso PrevDistance =< ?THRESHOLD ->
              timer:sleep(?CHANGE_SLEEP),
              stop(rotate_left),
              forward();
          Value when Value > ?THRESHOLD andalso PrevDistance > ?THRESHOLD ->
  