robot.swift

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": location.y += 1
      case "Down": location.y -= 1
      case "Left": location.x -= 1
      case "Right": location.x += 1
      default: break
    }
  }
}