# double ones from Boolos, Burgess & Jeffrey

0 1 1 l 2
2 _ _ l 3
2 1 1 l 3
3 _ 1 l 4
3 1 1 l 4
4 _ 1 r 5
4 1 1 r 5
5 1 1 r 5
5 _ _ r 6
6 1 1 r 6
6 _ _ l 7
7 1 _ l 8
7 _ _ l 8
8 _ _ l 11
8 1 1 l 9
9 1 1 l 9
9 _ _ l 10
10 1 1 l 10
10 _ _ r 2
11 1 1 l 11
11 _ _ r 12