Which kind of vehicle is the truck behind of?
The truck is behind the bus.
    src        edge_attr  dst
0     0   to the left of   10
1     0   to the left of   16
2     0   to the left of    2
3     1   to the left of    8
4     1  to the right of    6
5     1   to the left of    7
6     1  to the right of    4
7     2   to the left of    9
8     2   to the left of    3
9     2  to the right of   16
10    2  to the right of    0
11    3  to the right of   10
12    3  to the right of    7
13    3  to the right of    2
14    4  to the right of    6
15    4   to the left of    1
16    4               of   10
17    6   to the left of    4
18    6   to the left of    1
19    7  to the right of    1
20    7  to the right of   10
21    7   to the left of   15
22    7   to the left of    3
23    7           behind   10
24    8  to the right of    1
25    8  to the right of   10
26    9  to the right of    2
27    9  to the right of   16
28   10      in front of    7
29   10   to the left of    3
30   10  to the right of    0
31   10   to the left of   15
32   10   to the left of    8
33   10   to the left of    7
34   12               of   14
35   15  to the right of   10
36   15  to the right of    7
37   16   to the left of    9
38   16  to the right of    0
39   16   to the left of    2