Where is the train?
The train is on the floor.
    src        edge_attr  dst
0     0  to the right of    8
1     1   to the left of    2
2     1  to the right of    4
3     1  to the right of    8
4     2  to the right of    8
5     2  to the right of    4
6     2  to the right of    1
7     4   to the left of    2
8     4  to the right of    8
9     4   to the left of    1
10    6  to the right of    8
11    6           behind    7
12    7  to the right of    8
13    7      in front of    6
14    8               on    9
15    8   to the left of    2
16    8   to the left of    7
17    8   to the left of    0
18    8   to the left of    6
19    8   to the left of    4
20    8   to the left of    1