public function offsetGet($offset)
    {
        if (gettype($offset) !== 'string') {
            $msg = "The requested offset must be a non-empty string.";
            throw new OutOfRangeException($msg);
        }

        $returnValue = null;
        $data = &$this->getDataPlaceHolder();

        if (isset($data[$offset]) === true) {
            $returnValue = $data[$offset];
        }

        return $returnValue;
    }