WooCommerce - Reviews for product shortcode

<?php
// show approved reviews for product shortcode
// usage: [show_reviews product_id="1234"]
// code goes in functions.php for your child theme

add_shortcode('show_reviews', 'show_reviews');
function show_reviews($attributes) {
  $a = shortcode_atts( array('product_id' => 'product_id'), $attributes );
  $product_id = absint($a['product_id']);
  if (!$product_id) return;
  $args = array ('post_id' => $product_id, 'status' => 'approve');
  $comments = get_comments( $args );
  return wp_list_comments( array( 'callback' => 'woocommerce_comments', 'echo' => false ), $comments);
} // end function