What vehicle is it?
The vehicle is a train.
    src        edge_attr  dst
0     0   to the left of    2
1     1   to the left of    2
2     1  to the right of    3
3     2  to the right of    1
4     2  to the right of    0
5     2  to the right of    3
6     3               of    0
7     3   to the left of    2
8     3   to the left of    1
9     3  to the right of    4
10    4  to the right of    6
11    4   to the left of    3
12    6   to the left of    4