What kind of vehicle is to the left of the people?
The vehicle is a truck.
    src        edge_attr  dst
0     1          driving   14
1     2               on    3
2     2   to the left of   10
3     2  to the right of   14
4     2  to the right of   11
5     3  to the right of   14
6     3  to the right of   11
7     3   to the left of   10
8     7  to the right of    9
9     9   to the left of    7
10   10  to the right of   11
11   10  to the right of   14
12   10  to the right of    2
13   10  to the right of    3
14   11   to the left of   10
15   11   to the left of    3
16   11   to the left of    2
17   12               on    8
18   14               on    8
19   14   to the left of   10
20   14   to the left of    3
21   14   to the left of    2