What kind of vehicle is behind the truck?
The vehicle is a van.
    src        edge_attr  dst
0     0               at   16
1     0   to the left of    7
2     0   to the left of   12
3     1  to the right of    9
4     1   on the side of   12
..  ...              ...  ...
76   16  to the right of   14
77   16   to the left of   12
78   17   to the left of    9
79   17   to the left of   12
80   17           behind   12

[81 rows x 3 columns]