protocol Resizable {
    
    var width: Float { get set }
    var height: Float { get set }
    
    init(width: Float, height: Float)
    
    func resizeBy(wFactor: Float,
                  hFactor: Float)
}

class Rectangle: Resizable {
    var width: Float
    var height: Float
    
    required init(width: Float, height: Float) {
        self.width = width
        self.height = height
    }
    func resizeBy(wFactor: Float, hFactor: Float) {
        width *= wFactor
        height *= hFactor
    }
}