woocommerce_product_thumbnails_columns │ filter-hook │ WC 1.0

Usage

add_filter( 'woocommerce_product_thumbnails_columns', 'wp_kama_woocommerce_product_thumbnails_columns_filter' );

/**
 * Function for `woocommerce_product_thumbnails_columns` filter-hook.
 * 
 * @param  $4 
 *
 * @return 
 */
function wp_kama_woocommerce_product_thumbnails_columns_filter( $4 ){

	// filter...
	return $4;
}

$4

-

Where the hook is called

$columns           = apply_filters( 'woocommerce_product_thumbnails_columns', 4 );

Where the hook is used in WooCommerce