This example changes the current pset a couple of times and displays its membership:
(prism all) pset 0:12:2 (prism 0:12:2) pset The current set is defined as '0:12:2'. The set contains processes: 0,2,4,6,8,10,12. (prism 0:12:2) pset foo (prism foo) pset The current set is defined as 'foo'. The set contains processes: 0:3.