What is the horse walking through?
The horse is walking through the ocean.
    src        edge_attr  dst
0     5   to the left of   10
1     5   to the left of    6
2     6  to the right of   12
3     6  to the right of    5
4     7   to the left of    8
5     7   to the left of   10
6     8   to the left of   10
7     8  to the right of    7
8     9  to the right of   16
9     9               on    1
10    9  running through   13
11    9  walking through   13
12   10  to the right of    5
13   10  to the right of    8
14   10  to the right of    7
15   10  to the right of   12
16   12   to the left of   10
17   12   to the left of    6
18   15  to the right of   16
19   16   to the left of    9
20   16   to the left of   15