Duplicate length: 3
Original list: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
Duplicated list (cursor at `before'): Precondition 'not_off_unless_after' ... OK
Duplicated list (cursor at 4th item): 4, 5, 6
Duplicated list (cursor at 9th item): 9, 10
Duplicated list (cursor at 10th item): 10
Duplicated list (cursor at `after'): Empty? True
Execution completed