sclass Ext<A> extends DynamicObject implements IVar<A> {
  *() {}
  *(A *v) {}

  !include #1023196 // Var
  
  public bool equals(O o) {
    ret o instanceof Ext && o/Ext.v == v;
  }
  
  public int hashCode() { ret _hashCode(v); }
  
  // TODO: leave toString as it is or show fields too?
}