Are there flags or lamps?
Yes, there is a flag.
    src        edge_attr  dst
0     0   to the left of    6
1     0   to the left of   18
2     1  to the right of   13
3     1  to the right of   12
4     1   to the left of   19
5     2   to the left of   15
6     2   to the left of    5
7     2   to the left of    6
8     2   to the left of   14
9     3  to the right of    6
10    3   to the left of   16
11    4  to the right of    6
12    4   to the left of   16
13    5  to the right of   12
14    5  to the right of    2
15    6  to the right of    0
16    6   to the left of   19
17    6  to the right of   12
18    6  to the right of    2
19    6  to the right of   13
20    6   to the left of    3
21    6   to the left of    4
22    8   to the left of   16
23   10   to the left of   16
24   12   to the left of    5
25   12   to the left of   14
26   12   to the left of   18
27   12   to the left of   17
28   12   to the left of    6
29   12   to the left of    1
30   12   to the left of   15
31   13   to the left of    1
32   13   to the left of    6
33   14  to the right of   12
34   14  to the right of    2
35   15  to the right of   12
36   15  to the right of    2
37   16  to the right of    4
38   16  to the right of    3
39   16  to the right of    8
40   16  to the right of   10
41   17  to the right of   12
42   18  to the right of   12
43   18  to the right of    0
44   18   to the left of   19
45   19  to the right of    6
46   19  to the right of   18
47   19  to the right of    1