What color is the train?
The train is gray.
    src        edge_attr  dst
0     2  to the right of    5
1     2  to the right of   10
2     3   to the left of    9
3     3   to the left of    8
4     5   to the left of    8
5     5   to the left of    2
6     5  to the right of   10
7     8  to the right of    5
8     8  to the right of    3
9     8  to the right of   10
10    9  to the right of    3
11   10   to the left of    2
12   10   to the left of    5
13   10   to the left of    8