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