if (!function_exists('get_previous_post_link')) {
        function get_previous_post_link($label)
        {
                ob_start();
                previous_post_link($label);
                return ob_get_clean();
        }
}

if (!function_exists('get_next_post_link')) {
        function get_next_post_link($label)
        {
                ob_start();
                next_post_link($label);
                return ob_get_clean();
        }
}