// Compared to the ES6 class version:
class Class {
  constructor () { console.log(`This is the constructor.`) }
}
class Subclass extends Class {
  subclassMethod () { console.log(`This is a method on the subclass.`) }
}
// There is not really mixin support when using `extends`, so it's not really
// a fair comparison.
new Subclass().subclassMethod()