_navigation_markup example

$next = get_next_post_link(
        '<div class="nav-next">%link</div>',
        $args['next_text'],
        $args['in_same_term'],
        $args['excluded_terms'],
        $args['taxonomy']
    );

    // Only add markup if there's somewhere to navigate to.     if ( $previous || $next ) {
        $navigation = _navigation_markup( $previous . $next, $args['class'], $args['screen_reader_text'], $args['aria_label'] );
    }

    return $navigation;
}

/** * Displays the navigation to next/previous post, when applicable. * * @since 4.1.0 * * @param array $args Optional. See get_the_post_navigation() for available arguments. * Default empty array. */