What vehicle is to the left of the vehicle on the street?
The vehicle is a bus.
    src        edge_attr  dst
0     1   to the left of   13
1     2               on   20
2     2  to the right of   11
3     2  to the right of   10
4     2   to the left of    7
5     4               on    5
6     4  to the right of    9
7     4      waiting for   14
8     6               on    5
9     7  to the right of    2
10    7               on    8
11    7  to the right of   11
12    7  to the right of   10
13    7  to the right of   20
14    9               on    5
15    9   to the left of    4
16   10   to the left of    2
17   10   to the left of    7
18   10  to the right of   14
19   10               on   20
20   11   to the left of    7
21   11  to the right of   14
22   11   to the left of    2
23   12   to the left of   13
24   13  to the right of   18
25   13   to the left of   16
26   13  to the right of    1
27   13  to the right of   12
28   14   to the left of   10
29   14   to the left of   11
30   14  to the right of   17
31   16  to the right of   13
32   17               on   20
33   17   to the left of   14
34   18   to the left of   13
35   19               on   18
36   19        on top of   18
37   19        on top of   12
38   20   to the left of    7