public function decodeFiles(array $files)
    {
        // combine into one document.
        //
        $suiteDocument = new Document('phpbench');
        $rootEl = $suiteDocument->createRoot('phpbench');

        foreach ($files as $file) {
            $fileDom = new Document();
            $fileDom->load($file);

            foreach ($fileDom->query('./suite') as $suiteEl) {
                $importedEl = $suiteDocument->importNode($suiteEl, true);
                $rootEl->appendChild($importedEl);
            }
        }

        return $this->decode($suiteDocument);
    }