unresolved identifier error

Hi, I'm totally stuck at this point on the Swift Recap Part 2 challenge. No matter how I try to modify my code I still get some type of error message. The message I seem to get the most is "use of unresolved identifier 'y', use of unresolved identifier'x'." I understand what the error means (Swift can't figure out what 'x' and 'y' are) but I can't figure out how to fix it. I've tried Google but the info I've found is too broad for my specific problem. I've tried multiple variations of adding an override init to pass through x and y, and made multiple attempts to pass them directly to the overridden function, but I couldn't get it to work either way. Thanks!

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 am a machine!")
  }
}

// Enter your code below
class Robot: Machine {

  override func move(direction: String) {
    switch direction {
      case "Up": y += 1
      case "Down": y -= 1
      case "Left": x -= 1
      case "Right": x += 1
      default: break
    }
  }
}