: (las (1))
-> (1 1)
: (las @)
-> (2 1)
-> (1 2 1 1)
-> (1 1 1 2 2 1)
-> (3 1 2 2 1 1)
-> (1 3 1 1 2 2 2 1)
-> (1 1 1 3 2 1 3 2 1 1)
-> (3 1 1 3 1 2 1 1 1 3 1 2 2 1)