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

    protected function doFetch()
    {
        while ($element = $this->iterator->fetch()) {
            if ($this->endPosition !== null && $this->position >= $this->endPosition) {
                return null;
            } elseif ($this->position >= $this->startPosition) {
                $this->position++;
                return $element;
            } else {
                $this->position++;
            }
        }
    }