Is the train yellow or blue?
The train is yellow.
    src        edge_attr  dst
0     1  to the right of   11
1     1  to the right of    9
2     2  to the right of    3
3     2   to the left of    6
4     3   to the left of    2
5     3   to the left of    6
6     6   to the left of    9
7     6  to the right of    2
8     6  to the right of    3
9     6   to the left of   11
10    9  to the right of   11
11    9   to the left of    1
12    9  to the right of    6
13   11  to the right of    6
14   11   to the left of    9
15   11   to the left of    1