Cant see where I'm going wrong.....

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

let buttons: [String] = ["Up", "Down", "Left", "Right"]

class Robot: Machine {
    override func move(_ direction: String) {
        for button in buttons {
        switch button {
        case "Up": self.location.y =+ 1
        case "Down": self.location.y -= 1
        case "Left": self.location.x -= 1
        case "Right": self.location.x += 1
        default: print("invalid key entry")
        }
        }
    }
}