protected function _configureInstance($geshi)
    {
        if (empty($this->features)) {
            if (empty($this->configPath)) {
                $this->configPath = ROOT . DS . 'config' . DS;
            }
            if (file_exists($this->configPath . 'geshi.php')) {
                include $this->configPath . 'geshi.php';
            }
            return;
        }
        foreach ($this->features as $key => $value) {
            foreach ($value as &$test) {
                if (defined($test)) {
                    // convert strings to Geshi's constant values
                    // (exists possibility of name collisions)
                    $test = constant($test);
                }
            }
            unset($test);
            call_user_func_array(array($geshi, $key), $value);
        }
    }