protected function checkFiles($translatedFilePath = null, $sourceFilePath = null)
	{
		$errors = array();
		if($translatedFilePath!==null && !file_exists($translatedFilePath)) {
			$errors[] = 'Translation does not exist.';
		}

		if($sourceFilePath!==null && !file_exists($sourceFilePath)) {
			$errors[] = 'Source does not exist.';
		}

		return $errors;
	}