What is the boy on?
The boy is on the ski.
    src        edge_attr  dst
0     1   to the left of    3
1     2               on    1
2     2   to the left of    3
3     3  to the right of   11
4     3  to the right of    2
5     3  to the right of    1
6     4   to the left of   16
7     7  to the right of    8
8     7  to the right of   13
9     8   to the left of    7
10   10   to the left of   14
11   11               on   14
12   11   to the left of    3
13   13   to the left of    7
14   14  to the right of   15
15   14  to the right of   10
16   15   to the left of   14
17   16  to the right of    4