What color are the railroad tracks?
The railroad tracks are green.
    src        edge_attr  dst
0     0  to the right of   10
1     0               by    9
2     0  to the right of    9
3     1  to the right of    5
4     1   to the left of   18
5     1  to the right of   12
6     1   to the left of    8
7     1   to the left of    2
8     1   to the left of   14
9     1  to the right of    4
10    1  to the right of    3
11    1  to the right of    6
12    1  to the right of   13
13    2  to the right of    1
14    2  to the right of   18
15    3  to the right of   12
16    3  to the right of    6
17    3  to the right of   13
18    3   to the left of    1
19    4   to the left of    1
20    5   to the left of    1
21    6  to the right of   12
22    6  to the right of   13
23    6   to the left of    3
24    6   to the left of    1
25    7   to the left of   15
26    8   to the left of   17
27    8  to the right of    1
28    8   to the left of    9
29    9  to the right of   14
30    9   to the left of    0
31    9   to the left of   17
32    9  to the right of    8
33   10   to the left of   17
34   10   to the left of   15
35   10   to the left of    0
36   12               in    4
37   12   to the left of    1
38   12   to the left of    3
39   12   to the left of   13
40   12   to the left of    6
41   13  to the right of   12
42   13   to the left of    6
43   13   to the left of    3
44   13   to the left of    1
45   14  to the right of    1
46   14   to the left of    9
47   15  to the right of    7
48   15  to the right of   10
49   17  to the right of    9
50   17  to the right of    8
51   17  to the right of   10
52   18  to the right of    1
53   18   to the left of    2