What is the color of the vehicle at the station?
The train is gray.
    src        edge_attr  dst
0     0   to the left of    7
1     0   to the left of    8
2     1   to the left of    4
3     1   to the left of    2
4     1   to the left of    8
5     1   to the left of    7
6     2               on    3
7     2  to the right of    5
8     2   to the left of    7
9     2  to the right of    1
10    3               at    1
11    3  to the right of    6
12    4  to the right of    1
13    4  to the right of    5
14    4   to the left of    7
15    5   to the left of    2
16    5   to the left of    4
17    5   to the left of    7
18    6   to the left of    3
19    6               on    5
20    6     hanging from    5
21    7  to the right of    5
22    7  to the right of    4
23    7  to the right of    2
24    7  to the right of    0
25    7  to the right of    1
26    8  to the right of    1
27    8  to the right of    0
28    8               on    7
29    8  to the right of    9
30    9   to the left of    8