How to use the patchman.arch.models.MachineArchitecture.objects.get function in patchman

cursor.execute('SELECT * FROM host')
    rows = cursor.fetchall()

    plength = len(rows)
    pbar = progress_bar('Hosts', plength)
    i = 0

    for row in rows:
        pbar.update(i+1)
        i += 1
        
        host, created = Host.objects.get_or_create(
            hostname=row['host'],
            id=row['id'],
            arch=MachineArchitecture.objects.get(id=row['arch_id']),
            defaults={
                'ipaddress': row['report_ip'],
                'os': OS.objects.get(id=row['os_id']),
                'domain': Domain.objects.get(id=row['dmn_id']),
                'lastreport': row['pkgs_change_timestamp'],
                },
            tag=row['admin'],
            kernel=row['kernel']
            )
    cursor.close()

def import_repos(conn):

    cursor = conn.cursor(MySQLdb.cursors.DictCursor)

    cursor.execute('SELECT * FROM repositories')
    rows = cursor.fetchall()

    plength = len(rows)
    pbar = progress_bar('Repositories', plength)
    i = 0

    for row in rows:
        repo, c = Repository.objects.get_or_create(
            id=row['id'], name=row['name'], url=row['url'], security=row['is_sec'], enabled=row['enabled'],last_access_ok=row['last_access_ok'], file_checksum=row['file_checksum'], timestamp=row['timestamp'], arch=MachineArchitecture.objects.get(id=row['arch_id']))
        if row['type'] == "dpkg":
            repotype="D"
        elif row['type'] == "rpm":
            repotype="R"
        repo.repotype = repotype
        repo.save()
        pbar.update(i+1)
        i += 1

    cursor = conn.cursor(MySQLdb.cursors.DictCursor)
    cursor.execute('SELECT pkgs.name, act_version.arch, act_version.act_version, act_version.act_rel, repositories.id FROM (act_version inner join repositories on act_version.repo_id = repositories.id) inner join pkgs on act_version.pkg_id = pkgs.id')
    rows = cursor.fetchall()

    plength = len(rows)
    pbar = progress_bar('Creating Package<->Repo Links', plength)
    i = 0

for i, p in enumerate(parches):
            a = PackageArchitecture.objects.get(name=p.name)
            a.delete()
            update_pbar(i + 1)

    marches = MachineArchitecture.objects.filter(host__isnull=True,
                                                 repository__isnull=True)
    mlen = marches.count()

    if mlen == 0:
        if verbose:
            print 'No orphaned machine architectures found.'
    else:
        create_pbar('Removing {0!s} orphaned m arches:'.format(mlen), mlen)
        for i, m in enumerate(marches):
            a = MachineArchitecture.objects.get(name=m.name)
            a.delete()
            update_pbar(i + 1)