What animal is in the pen?
The zebras are in the pen.
    src        edge_attr  dst
0     0   to the left of    7
1     1  to the right of    6
2     2  to the right of    6
3     4  to the right of    6
4     6   to the left of    1
5     6   to the left of    9
6     6   to the left of    4
7     6   to the left of    8
8     6   to the left of    2
9     7  to the right of    0
10    7  to the right of    8
11    8   to the left of    7
12    8  to the right of    6
13    9               in   10
14    9  to the right of    6