function woocommerce_get_product_subcategories( $parent_id = 0 ) {
		$parent_id          = absint( $parent_id );
		$cache_key          = apply_filters( 'woocommerce_get_product_subcategories_cache_key', 'product-category-hierarchy-' . $parent_id, $parent_id );
		$product_categories = $cache_key ? wp_cache_get( $cache_key, 'product_cat' ) : false;

		if ( false === $product_categories ) {
			// NOTE: using child_of instead of parent - this is not ideal but due to a WP bug ( https://core.trac.wordpress.org/ticket/15626 ) pad_counts won't work.
			$product_categories = get_categories(
				apply_filters(
					'woocommerce_product_subcategories_args',
					array(
						'parent'       => $parent_id,
						'hide_empty'   => 0,
						'hierarchical' => 1,
						'taxonomy'     => 'product_cat',
						'pad_counts'   => 1,
					)
				)
			);

			if ( $cache_key ) {
				wp_cache_set( $cache_key, $product_categories, 'product_cat' );
			}
		}

		if ( apply_filters( 'woocommerce_product_subcategories_hide_empty', true ) ) {
			$product_categories = wp_list_filter( $product_categories, array( 'count' => 0 ), 'NOT' );
		}

		return $product_categories;
	}