def main(request, response):
    """
    Respond with a blank HTML document and a `Link` header which describes
    a link relation specified by the requests `location` and `rel` query string
    parameters
    """
    headers = [
        (b'Content-Type', b'text/html'),
        (
          b'Link',
          b'<' + request.GET.first(b'location') + b'>; rel=' + request.GET.first(b'rel')
        )
    ]
    return (200, headers, b'')