protected function dataForPrefix($namespace, $prefix)
    {
        if (!isset($this->cachedData[$namespace][$prefix])) {
            $this->loadDataForPrefix($namespace, $prefix);

        }

        // If no custom data was setted using offsetSet() just return that
        if (!isset($this->customData[$namespace][$prefix])) {
            return $this->cachedData[$namespace][$prefix];
        }

        $data = $this->cachedData[$namespace][$prefix];

        array_unshift($data, $this->customData[$namespace][$prefix]);

        return $data;

    }