(set-threads 2)
(set-files 1)
(lock 0 0)
(match (locked 0 0))
(lock 1 0)
(match (epsilon))
(unlock 0 0)
(match
  (all (locked 1 0)
       (unlocked 0 0)))
(unlock 1 0)
(match (unlocked 1 0))
