What is the vehicle that the building is behind of?
The vehicle is a bus.
    src        edge_attr  dst
0     0  to the right of    8
1     0  to the right of    4
2     1  to the right of   14
3     2  to the right of    4
4     2  to the right of   11
5     2  to the right of    3
6     3   to the left of    2
7     4      in front of    7
8     4   to the left of    2
9     4   to the left of    0
10    7           behind    4
11    8   to the left of    0
12    9   on the side of    4
13    9   to the left of   13
14   11   to the left of    2
15   13  to the right of    9
16   13   on the side of    4
17   14        riding on    4
18   14   to the left of    1
19   14   sitting inside    4