Who is the bike pushed by?
The bike is pushed by the boy.
    src        edge_attr  dst
0     2  to the right of    8
1     2  to the right of   11
2     5   to the left of    8
3     5          wearing   16
4     5   to the left of   11
5     6          wearing    7
6     8   to the left of    2
7     8  to the right of    5
8     8  to the right of   16
9     9          wearing   10
10    9          wearing   17
11    9          pushing   14
12    9               on    0
13   11   to the left of   18
14   11  to the right of    5
15   11   to the left of    2
16   12   to the left of   19
17   13   to the left of   20
18   14        pushed by    9
19   16   to the left of    8
20   18  to the right of   11
21   18               on    0
22   19  to the right of   12
23   20  to the right of   21
24   20  to the right of   13
25   21   to the left of   20