source: lightning/7.1.0/sidebar-page.php

<?php
if ( is_active_sidebar( 'common-side-top-widget-area' ) ) {
        dynamic_sidebar( 'common-side-top-widget-area' );
}

// Display post type widget area
$widdget_area_name = 'page-side-widget-area';
if ( is_active_sidebar( $widdget_area_name ) ) {
        dynamic_sidebar( $widdget_area_name );
} else {

        if ( $post->ancestors ) {
                foreach ( $post->ancestors as $post_anc_id ) {
                        $post_id = $post_anc_id;
                } // foreach($post->ancestors as $post_anc_id){
        } else {
                $post_id = $post->ID;
        } // if($post->ancestors){

        if ( $post_id ) {
                $children = wp_list_pages( 'title_li=&child_of=' . $post_id . '&echo=0' );
                if ( $children ) { ?>
                        <aside class="widget widget_child_page widget_link_list">
                        <nav class="localNav">
                        <h1 class="subSection-title"><?php echo get_the_title( $post_id ); ?></h1>
                        <ul>
                        <?php echo $children; ?>
                        </ul>
                        </nav>
                        </aside>
                <?php } // if ($children)
        } // if ($post_id)

} // if ( is_active_sidebar( $widdget_area_name ) ){

if ( is_active_sidebar( 'common-side-bottom-widget-area' ) ) {
        dynamic_sidebar( 'common-side-bottom-widget-area' );
}
?>