Here the value we want to return, wrappedValue, is optional. And we don't want it to be. So we create a private var of a new variable, height, assign it a value, and then in the computeted property get and set the wrapped one which we really care about.
struct SmallRectangle {
private var _height = 0
private var _width = 0
var height: Int {
get { return _height.wrappedValue }
set { _height.wrappedValue = newValue }
}
var width: Int {
get { return _width.wrappedValue }
set { _width.wrappedValue = newValue }
}
}