def make_users_groups_url(base_url, duke_unique_id):
    """
    Create url for fetching a users groups.
    :param base_url: base group manager url (eg. 'https://groups.oit.duke.edu/grouper-ws/servicesRest/json/v2_1_500/')
    :param duke_unique_id: str: unique id (number) of the user we want to build a url for
    :return: str: url we created
    """
    return "{}/subjects/{}/groups".format(base_url, duke_unique_id)