map( key: [url, pagerank], value: outlink_list )

    for each outlink in outlink_list

        emit( key: outlink, value: pagerank/size(outlink_list) )

    emit( key: url, value: outlink_list )

reducer( key: url, value: list_pr_or_urls )

    outlink_list = []

    pagerank = 0

    for each pr_or_urls in list_pr_or_urls

        if is_list( pr_or_urls )

            outlink_list = pr_or_urls

        else

            pagerank += pr_or_urls

    pagerank = 1 - DAMPING_FACTOR + ( DAMPING_FACTOR * pagerank )

    emit( key: [url, pagerank], value: outlink_list )