Pinq\Iterators\Common\JoinOnIterator::innerElementFilter PHP Method

    protected final function innerElementFilter($outerKey, $outerValue)
    {
        $filter = $this->filter;
        return function ($innerValue, $innerKey) use($filter, $outerKey, $outerValue) {
            return $filter($outerValue, $innerValue, $outerKey, $innerKey);
        };
    }