class ModalProvider {
   static func makeModalWindowOne(callback)  {
       AcceptButton acceptButton = new AcceptButton()
       ModalWindow mw = new ModalWindow()
       mw.addButton(acceptButton)
       acceptButton.onClick() {
          callback()
       }
   }
   static func makeModalWindow2(callback) {
   // similar to previous but with different number of buttons
   }

}