What's wrong here?

class Point {
  var x: Int
  var y: Int

  init(x: Int, y: Int) {
    self.x = x
    self.y = y
  }
}

class Machine {
  var location: Point

  init() {
    self.location = Point(x: 0, y: 0)
  }

  func move(_ direction: String) {
    print("Do nothing! Im a machine!")
  }
}

// Enter your code below

class Robot: Machine {
  override func move(_ direction: String) {
  switch direction{
    case "Up":
      self.location.y  = self.location.y + 1
    case "Down":
      self.location.y = self.location.y - 1
    case "Right":
      self.location.x = self.location.x - 1
    case "Left":
      self.location.x = self.location.x - 1
    default:
      break
    }
  }