protected function processLanguageTaggedPropertyValue($propertyValue)
    {
        $language = null;
        if (is_object($propertyValue)) {
            // If this is an invalid language tagged object
            if (!isset($propertyValue->lang) || !isset($propertyValue->value)) {
                throw new RuntimeException(
                    RuntimeException::INVALID_LANGUAGE_TAGGED_VALUE_STR,
                    RuntimeException::INVALID_LANGUAGE_TAGGED_VALUE
                );
            }

            $language      = $propertyValue->lang;
            $propertyValue = $propertyValue->value;
        }

        return [$propertyValue, $language];
    }