property accessors in Swift

struct Angle {
  var degrees: Double
  var radians: Double {
    @storageRestrictions(initializes: degrees) // 👈🏼
    init(initialValue)  {
      degrees = initialValue * 180 / .pi
    }
 
    get { degrees * .pi / 180 }
    set { degrees = newValue * 180 / .pi }
  }
 
  init(degrees: Double) {
    self.degrees = degrees // initializes 'self.degrees' directly
  }
 
  init(radiansParam: Double) {
    self.radians = radiansParam // calls init accessor for 'self.radians', passing 'radiansParam' as the argument
  }
}