Who is balancing on the skateboard that is in the middle?
The skater is balancing on the skateboard.
    src        edge_attr  dst
0     0             near   18
1     0             near    3
2     0  to the right of    8
3     1   to the left of    5
4     1            below   20
5     1           behind    3
6     1   to the left of    4
7     2   to the left of   17
8     3               on   20
9     3          wearing   13
10    3          wearing   14
11    3          wearing   12
12    3        riding on   20
13    3     balancing on   20
14    3          wearing   11
15    3      in front of    1
16    3  to the right of   23
17    3             near    0
18    4  to the right of    6
19    4  to the right of    1
20    5  to the right of    1
21    6   to the left of    4
22    7   to the left of   11
23    8   to the left of    0
24    8   to the left of   19
25    8   to the left of   22
26   11  to the right of    7
27   15   to the left of   22
28   16   to the left of   19
29   17  to the right of    2
30   18             near    0
31   19  to the right of    8
32   19  to the right of   21
33   19  to the right of   16
34   20  to the right of   23
35   21   to the left of   19
36   22  to the right of    8
37   22  to the right of   15
38   23   to the left of   20
39   23   to the left of    3