What animal does the cowboy ride?
The cowboy rides a horse.
    src        edge_attr  dst
0     2   to the left of    5
1     2   to the left of    7
2     2   to the left of   12
3     3               of    7
4     3  to the right of    9
5     3  to the right of   12
6     5   to the left of    7
7     5  to the right of    2
8     7  to the right of    2
9     7  to the right of   12
10    7  to the right of    5
11    9          wearing    4
12    9          wearing    6
13    9           riding    7
14    9   to the left of    3
15    9               on    7
16   12   to the left of    7
17   12   to the left of    3
18   12  to the right of    2