def duration(seconds, _maxweeks=99999999999):
    return ', '.join('%d %s' % (num, unit)
             for num, unit in zip([(seconds // d) % m
                       for d, m in ((604800, _maxweeks),
                                                        (86400, 7), (3600, 24),
                                                        (60, 60), (1, 60))],
                      ['wk', 'd', 'hr', 'min', 'sec'])
             if num)