618   $ try --optimize '(9)%(5)'

   619   (only

   620     (group

   621       ('symbol', '9'))

   622     (group

   623       ('symbol', '5')))

   624   * optimized:

   625   (func

   626     ('symbol', 'only')

   627     (list

   628       ('symbol', '9')

   629       ('symbol', '5')))

   630   * set:

   631   <baseset+ [8, 9, 2, 4]>

   632   2

   633   4

   634   8

   635   9