Which kind of vehicle is behind the truck?
The vehicle is a bus.
    src        edge_attr  dst
0     0  to the right of    7
1     0  to the right of    3
2     1   to the left of    9
3     1  to the right of   10
4     2  to the right of    7
5     2          driving    8
6     3   to the left of    8
7     3  to the right of   15
8     3   to the left of    0
9     4   to the left of    9
10    4  to the right of    5
11    4  to the right of   10
12    5   to the left of    4
13    5  to the right of   10
14    6  to the right of   10
15    7            above   15
16    7      in front of    8
17    7   to the left of    8
18    7               on   15
19    7   to the left of    0
20    7  to the right of   15
21    7   to the left of    2
22    8           behind    7
23    8  to the right of    7
24    8  to the right of   12
25    8  to the right of    3
26    9  to the right of   11
27    9  to the right of    1
28    9  to the right of    4
29   10   to the left of    1
30   10   to the left of    6
31   10   to the left of    5
32   10             near   15
33   10   to the left of    4
34   11            above    1
35   11   to the left of    9
36   11            above    6
37   12  to the right of   13
38   12  to the right of   15
39   12   to the left of    8
40   13  to the right of   15
41   13   to the left of   12
42   14             near   15
43   14   to the left of   15
44   14           beside   15
45   14          next to   15
46   15          next to   10
47   15   to the left of   12
48   15   to the left of   13
49   15  to the right of   14
50   15   to the left of    3
51   15   to the left of    7
52   15             near   14