Please tell me what I did wrong for this enumeration code challenge?

I tried to follow the directions and examples, but it didn't work. Where did I go wrong?

In the editor below you have two objects - classes named Point and Robot. The Robot stores its location as a point instance and contains a move function.

The task of this challenge is to complete the implementation for move. Move takes a parameter of type Direction which is an enumeration listing the possible movement directions.

When you tell the robot to move up (by specifying Direction.Up as the argument), the y coordinate should increase by 1. Similarly moving down means the y coordinate decreases by 1, moving right means the x coordinate increases by 1 and finally left means x decreases by 1.

class Point {
    var x: Int
    var y: Int

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

enum Direction {
    case left
    case right
    case up
    case down
}

class Robot {
    var location: Point

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

    func move (direction: Direction) {
        // Enter your code below
        switch direction {
          case .left: return location.x -= 1
          case .right: return location.x += 1
          case .up: return location.y += 1
          case .down: return location.y -= 1
         }
    }
}