sclass Ext<A> extends DynamicObject implements IVar<A> {
  *() {}
  *(A *v) {}
  //O equalityPredicate; // func(Ext, Ext) -> bool

  !include #1023196 // Var
  
  public bool equals(O o) {
    ret o instanceof Ext && eq(o/Ext.v, v);
  }
  
  public int hashCode() { ret _hashCode(v); }
  
  // Note: toString will just forward to the value
}