SoompiBlog - Reversible.swift

import Foundation

protocol Reversible {
  var isOn: Bool { get set }

  mutating func reverse()
  func reversed() -> Self
}

extension Reversible {
  mutating func reverse() {
    isOn = !isOn
  }

  func reversed() -> Self {
    var new = self
    new.reverse()
    return new
  }
}