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