def next_page_link(link_header):
    """
    The link_header will be of the form:
    <(url)>; rel="(relation)", <(url2)>; rel="<(relation2)>"

    Where:
    (url) will be a pointer to a page on GitHub's API
    (relation) will be first, next, prev, or last
    (url2) will be a pointer to a different page on GitHub's API

    A link_header will always have two pairs of URLs. Next and last are
    paired and first and prev are paired.

    :param link_header: The content of the Link: header from GitHub API
    :return: url for the next page of the API results or None if no next link
    """
    next_page_url = None
    for url in link_header.split(', '):
        if 'rel="next"' in url:
            next_page_url = url.split('; ')[0].strip('<>')

    return next_page_url