Can's figure this one out. I need help :D

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! I'm a machine!")
  }
}


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