/**
 *
 * Any Custom Post options filter
 * the filter format name is: 'flo_'.$any_custom_post_option[$url_args['query']].'_fields_key'
 * in our case the $any_custom_post_option[$url_args['query']] = books
 *
 */
add_filter('flo_books_fields_key', 'flo_cannes_books_fields_key');
function flo_cannes_books_fields_key() {
	return 'field_5b50a9e4e602b';
}