def fix_url(url):
    """
    The BGG API started returning URLs like //cf.geekdo-images.com/images/pic55406.jpg for thumbnails and images.
    This function fixes them.

    :param url: the url to fix
    :return: the fixed url
    """
    if url and url.startswith('//'):
        url = 'http:{}'.format(url)
    return url
