How to use the clldutils.apilib.assert_release function in clldutils

def load(args):
    glottolog = args.repos
    fts.index('fts_index', models.Ref.fts, DBSession.bind)
    DBSession.execute("CREATE EXTENSION IF NOT EXISTS unaccent WITH SCHEMA public;")
    version = assert_release(glottolog.repos)
    dataset = common.Dataset(
        id='glottolog',
        name="{0} {1}".format(glottolog.publication.web.name, version),
        publisher_name=glottolog.publication.publisher.name,
        publisher_place=glottolog.publication.publisher.place,
        publisher_url=glottolog.publication.publisher.url,
        license=glottolog.publication.license.url,
        domain=purl.URL(glottolog.publication.web.url).domain(),
        contact=glottolog.publication.web.contact,
        jsondata={'license_icon': 'cc-by.png', 'license_name': glottolog.publication.license.name},
    )
    data = Data()

    for e in glottolog.editors.values():
        if e.current:
            ed = data.add(common.Contributor, e.id, id=e.id, name=e.name)

domainelement_pk=mapk,
                valueset=vs))

    for vs in DBSession.query(common.ValueSet)\
            .join(common.Language)\
            .join(common.Parameter)\
            .filter(common.Parameter.id == 'macroarea')\
            .options(joinedload(common.ValueSet.values), joinedload(common.ValueSet.language)):
        vs.language.macroareas = ', '.join([macroareas[v.domainelement_pk][1] for v in vs.values])

    for row in list(DBSession.execute(
        "select pk, pages, pages_int, startpage_int from source where pages_int < 0"
    )):
        raise ValueError(row)

    version = assert_release(args.repos.repos)
    with jsonlib.update(gc2version(args), indent=4) as legacy:
        for lang in DBSession.query(common.Language):
            if lang.id not in legacy:
                lang.update_jsondata(new=True)
                legacy[lang.id] = version

    valuesets = {
        r[0]: r[1] for r in DBSession.query(common.ValueSet.id, common.ValueSet.pk)}
    refs = {
        r[0]: r[1]
        for r in DBSession.query(models.Refprovider.id, models.Refprovider.ref_pk)}

    for vsid, vspk in valuesets.items():
        if vsid.startswith('macroarea-'):
            DBSession.add(common.ValueSetReference(
                source_pk=refs[args.repos.macroareas.__defaults__['reference_id']],

def run(args):
    version = assert_release(args.repos.repos)
    if args.previous:
        last = args.previous
    else:
        rels = get_releases(args)
        last = sorted(set(rel.tag for rel in rels) - {version}, key=lambda s: float(s[1:]))[-1][1:]
    print('previous version: {0}'.format(last))

    cdb = create_engine('postgresql://postgres@/glottolog3')
    ldb = create_engine('postgresql://postgres@/glottolog-{0}'.format(last))
    sql = "select id from language as l, languoid as ll where l.pk = ll.pk and ll.level = 'language'"

    current = set(r[0] for r in cdb.execute(sql))
    last = set(r[0] for r in ldb.execute(sql))
    for gc in sorted(current - last):
        cdb.execute(
            "update language set updated = %s where id = %s", (datetime.utcnow(), gc))