What is on the animal that is to the left of the fence?
The mask is on the horse.
    src        edge_attr  dst
0     0               on    1
1     0   to the left of    8
2     0   to the left of    3
3     1   to the left of    3
4     3  to the right of    5
5     3  to the right of    1
6     3  to the right of    8
7     3  to the right of    0
8     5   to the left of    3
9     8   to the left of    3
10    8  to the right of    0