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