Where is the train?
The train is on the railroad.
    src        edge_attr  dst
0     1   to the left of    4
1     1   to the left of    8
2     1  to the right of   15
3     1  to the right of   13
4     1  to the right of   16
5     2   to the left of   12
6     3   to the left of    8
7     3   to the left of    4
8     4               on   12
9     4  to the right of    1
10    4  to the right of   13
11    4  to the right of    3
12    4  to the right of   14
13    4  to the right of   11
14    4  to the right of   16
15    4  to the right of   15
16    5  to the right of    9
17    8  to the right of    3
18    8  to the right of    1
19    9   to the left of    5
20   10   to the left of   14
21   10   to the left of   11
22   10   to the left of   13
23   10   to the left of   15
24   10   to the left of   16
25   11   to the left of    4
26   11  to the right of   10
27   11  to the right of   13
28   12  to the right of    2
29   13   to the left of    1
30   13   to the left of    4
31   13   to the left of   15
32   13   to the left of   16
33   13  to the right of   10
34   13   to the left of   11
35   14   to the left of    4
36   14  to the right of   10
37   15  to the right of   10
38   15   to the left of    4
39   15  to the right of   16
40   15  to the right of   13
41   15   to the left of    1
42   16   to the left of    4
43   16  to the right of   10
44   16  to the right of   13
45   16   to the left of   15
46   16   to the left of    1