Pagination on pages

pagination_on_pages.php

<?php
  $q = new WP_Query( array( 'post_type' => 'page', 'post_parent' => $page_ID, 'depth' => 1, 'posts_per_page' => 4, 'paged' => ( get_query_var('paged') ? get_query_var('paged') : 1) )  );
  if ( $q->have_posts() ) : while ( $q->have_posts() ) : $q->the_post();
?>
<?php endwhile;
   if ( get_option('permalink_structure') ) {
       $format = 'page/%#%';
   } else {
       $format = '&paged=%#%';
   }
   $paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
   $args2 = array(
       'base' => get_permalink( $post->post_parent ) . '%_%',
       'format' => $format,
       'current' => $paged,
       'total' => $q->max_num_pages
   ); ?>
   </div>
   <div class="row"><div class="col-xs-12 pagination">
   <?php echo paginate_links( $args2 ); ?>
   </div></div>
<?php wp_reset_query(); endif ?>