text: // classes cannot extend primitives
  
  class C extends number { }
  class C2 extends string { }
  class C3 extends boolean { }
  class C4 extends Void  { }
  class C4a extends void {}
  class C5 extends Null { }
  class C5a extends null { }
  class C6 extends undefined { }
  class C7 extends Undefined { }
  
  enum E { A }
  class C8 extends E { }