woocommerce_before_output_product_categories │ filter-hook │ WC 1.0

Usage

add_filter( 'woocommerce_before_output_product_categories', 'wp_kama_woocommerce_before_output_product_categories_filter' );

/**
 * Function for `woocommerce_before_output_product_categories` filter-hook.
 * 
 * @param  $string 
 *
 * @return 
 */
function wp_kama_woocommerce_before_output_product_categories_filter( $string ){

	// filter...
	return $string;
}

$string

-

Where the hook is called

'before'    => apply_filters( 'woocommerce_before_output_product_categories', '' ),

Where the hook is used in WooCommerce