What is the horse pulling?
The horse is pulling the carriage.
    src        edge_attr  dst
0     0  to the right of   13
1     0  to the right of   11
2     0   to the left of   14
3     0   to the left of    4
4     0  to the right of    3
5     0   to the left of    9
6     2  to the right of    4
7     2        pulled by    5
8     3   to the left of   10
9     3  to the right of   13
10    3   to the left of    8
11    3   to the left of    0
12    4  to the right of    0
13    4   to the left of    5
14    4   to the left of    2
15    4  to the right of    9
16    4  to the right of   14
17    4  to the right of   10
18    4         crossing    8
19    5  to the right of    4
20    5  to the right of    9
21    5  to the right of   14
22    5          pulling    2
23    8  to the right of    3
24    9               in    8
25    9  to the right of   10
26    9  to the right of   11
27    9  to the right of    0
28    9   to the left of    4
29    9   to the left of    5
30    9               on    8
31   10  to the right of   13
32   10   to the left of   14
33   10   to the left of    4
34   10  to the right of    3
35   10   to the left of    9
36   10  to the right of   11
37   11   to the left of   10
38   11   to the left of    0
39   11   to the left of    9
40   13   to the left of    0
41   13   to the left of    3
42   13   to the left of   10
43   14   to the left of    5
44   14   to the left of    4
45   14  to the right of   10
46   14  to the right of    0