Pinq\Iterators\Standard\IteratorAdapter::doFetch PHP Метод

    protected function doFetch()
    {
        $iterator = $this->iterator;
        if ($iterator->valid()) {
            $element = [$iterator->key(), $iterator->current()];
            $iterator->next();
            return $element;
        }
    }

 protected function doFetch()
 {
     if (parent::doFetch() !== null) {
         return [$this->currentKey, &$this->currentValue];
     }
 }