public function addNamedRange(NamedRange $namedRange)
    {
        if ($namedRange->getScope() == null) {
            // global scope
            $this->namedRanges[$namedRange->getName()] = $namedRange;
        } else {
            // local scope
            $this->namedRanges[$namedRange->getScope()->getTitle() . '!' . $namedRange->getName()] = $namedRange;
        }

        return true;
    }