override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
   super.onViewCreated(view, savedInstanceState)
   //...
   presenter = PhotosPresenter(arguments!!.getString(EXTRA_PHOTO))
   setUpRecyclerView()
}

private fun setUpRecyclerView() {
   rvPhotos!!.addOnScrollListener(object : GridScrollListener(gridLayoutManager!!) {
       override fun loadMoreItems() {
           showProgress()
           presenter!!.loadMore()
       }
       //...
   })
}