What type of vehicle is this?
That is a train.
    src        edge_attr  dst
0     0   to the left of    7
1     0   to the left of    6
2     0   to the left of    4
3     0   to the left of    1
4     1   to the left of    4
5     1  to the right of    0
6     1   to the left of    7
7     1   to the left of    6
8     3   to the left of    5
9     3  to the right of    4
10    4  to the right of    7
11    4  to the right of    1
12    4  to the right of    0
13    4  to the right of    6
14    4   to the left of    3
15    5  to the right of    3
16    6  to the right of    0
17    6  to the right of    1
18    6   to the left of    4
19    6   to the left of    7
20    7  to the right of    0
21    7  to the right of    1
22    7   to the left of    4
23    7  to the right of    6