WordPress 前後の記事を取得・出力

<?php $previous_post = get_previous_post(); ?>
<?php $next_post = get_next_post(); ?>
<?php if (!empty( $previous_post )): ?>
	<?php
		$args = array(
		'post_type' => 'POST_TYPE_NAME',
		'posts_per_page' => '1',
		'post__in' => array( $previous_post->ID )
		);
	?>
	<?php $loop = new WP_Query( $args ); ?>
	<?php if($loop -> have_posts()): ?>
	<?php while($loop -> have_posts()): $loop->the_post();?>
		<!-- loop -->
	<?php endwhile; ?>
	<?php endif; ?>
	<?php wp_reset_postdata(); ?>
<?php endif; ?>